Organic semiconductor material

ABSTRACT

The purpose of the present invention is to provide an organic semiconductor material having liquid crystallinity and high electron mobility. The present invention is an organic semiconductor material having at least a charge-transporting molecular unit (A) having a structure of an aromatic fused ring system and a cyclic structural unit (B) bonded to the aforementioned unit via a single bond, wherein the unit (A) and/or the unit (B) has a side chain composed of a unit (C), and wherein the organic semiconductor material exhibits a liquid crystal phase that is different from an N-phase, an SmA-phase or an SmC-phase.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application of PCT/JP2012/056184,filed Mar. 9, 2012, which claims priority from Japanese application JP2011-053642, filed Mar. 10, 2011.

TECHNICAL FIELD

The present invention relates to an organic semiconductor material,which is suitably usable for various devices, such as organic electronicdevice. More specifically, the present invention relates to an organicsemiconductor material having a liquid crystallinity.

BACKGROUND ART

An organic substance capable of transporting electronic charges bypositive hole or electron can be used as an organic semiconductor, andcan be used as a material for organic electronic devices, such asphotoreceptors for copying machines, photosensors, organic EL(electroluminescence) devices, organic transistors, organic solar cellsand organic memory devices.

Such a material may generally be used in the form of an amorphous thinfilm or a polycrystalline thin film. On the other hand, in recent years,there has been found an electronic conduction exhibiting a much highermobility than that of an amorphous organic semiconductor occurring in aliquid crystal phase of a liquid crystal substance, which has heretoforebeen considered as an ion conductive substance, and further it has beenrecognized that the liquid crystal phase is usable as an organicsemiconductor.

Such a liquid crystal substance may be positioned as a new type oforganic semiconductor, which is capable of forming a molecular condensedphase (i.e., liquid crystal phase), which is oriented in aself-organizing manner and exhibits a high mobility (10⁻⁴ cm²/Vs to 1cm²/Vs). In addition, such a liquid crystal substance has been found tohave an excellent property, which conventional amorphous organicsemiconductor materials or crystalline organic semiconductor materialscannot exhibit. More specifically, the liquid crystal substance ischaracterized in that an orientation defect specific to a liquidcrystal, such as domain interface or disclination, scarcely allows forthe formation of an electrically active level. In practice, anelectronic device such as photosensor, electrophotographicphotoreceptor, organic EL device, organic transistor and organic solarcell is being produced on trial by using a liquid crystal phase as anorganic semiconductor.

The liquid crystal substance has a prominent characteristic such that ingeneral, molecular orientation, which is hard to be controlled in anon-liquid crystal substance, can easily be controlled in a liquidcrystal phase. For example, a rod-like liquid crystal substancegenerally has a tendency that, when the liquid crystal substance isinjected between two substrates as in the case of a liquid crystal cell,the liquid crystal molecules are liable to be oriented in a statewherein the molecular major axis thereof lies almost parallel to thesubstrate surface at a liquid crystal phase temperature, and when theliquid crystal substance is applied onto a substrate, the molecules areliable to be oriented in a state wherein the molecular long axis thereofrises almost perpendicular to the substrate surface. The utilization ofthis property makes it easy to produce a thin film (crystalline thinfilm) having a controlled molecular orientation not only in a liquidcrystal phase but also in a crystal phase by lowering the temperature ofthe thin film liquid crystal which has been oriented at a liquid crystalphase temperature, to thereby cause a phase transition to a crystalphase. This is difficult to be realized in the case of an ordinarynon-liquid crystalline organic material.

It has been reported that a crystal thin film excellent in thecrystallinity or flatness can be produced, when a liquid crystal thinfilm (i.e., a thin film in the state of a liquid crystal phase) of aliquid crystal substance is utilized as a precursor at the formation ofa crystal thin film by using the above-described characteristics.

According to this technique, a uniform film excellent in the surfaceflatness may be obtained by forming a liquid crystal film at a liquidcrystal phase temperature, and then cooling the resulting liquid crystalfilm to a crystallization temperature. In view of such an applicabilityof the liquid crystal substance to an electronic device as an organicsemiconductor material, not only in the form of a liquid crystal thinfilm but also in the form of a crystalline thin film, the liquid crystalsubstance may be a material having a high degree of freedom as anorganic semiconductor (see, for example, Non-Patent Document 1: AdvancedMaterials, electronic edition, 25 FEB 2011, DOI:10.1002/adma.201004474).

However, when a liquid crystal substance is intended to be used as anorganic semiconductor, it is necessary to obtain a liquid crystalsubstance exhibiting a high electron mobility. In this connection, in anattempt to obtain a substance exhibiting a high electron mobility, thereis posed a problem such that what kind of a substance should besynthesized.

Heretofore, various materials have been synthesized as a liquid crystalsubstance, but the target thereof has been substantially limited to anematic liquid crystal to be used as a display material for a displaydevice utilizing optical anisotropy. Accordingly, a guideline formolecular design of a liquid crystal substance, which is suitable forthe liquid crystal substance as an organic semiconductor, that is, a wayof thinking in which the liquid crystal substance may be synthesized,has never been clarified.

Accordingly, in the prior art, in an attempt to synthesize a novelliquid crystal substance exhibiting a high electron mobility, there hasbeen no method except for a trial-and-error method wherein, basically,an aromatic ring-containing core structure and a hydrocarbon chain iscombined so as to select a desired chemical structure, and after theactual synthesis of the substance, the liquid crystal phase exhibited bythe substance is examined. In addition, a useful guideline has not beenprovided for designing a structure suitable for an organic semiconductorexhibiting a high mobility, and the synthesis has encountered greatdifficulty in developing such a material.

PRIOR ART DOCUMENTS

[Non-Patent Document 1] Advanced Materials, electronic edition, 25 FEB2011, DOI: 10.1002/adma.201004474

SUMMARY OF THE INVENTION

An object of the present invention is to solve the above-describedproblem encountered in the prior art and to provide an organicsemiconductor material not only liquid crystallinity but also exhibitinga high electron mobility.

As a result of earnest study, the present inventors have found that amaterial having at least a specific charge transporting molecular unit Aand a cyclic structure unit B linked to the unit A by a single bond isvery suitable as the above-described organic semiconductor material.

The organic semiconductor material according to the present invention isbased on such a discovery. More specifically, the organic semiconductormaterial according to the present invention comprises, at least: acharge transporting molecular unit A having an aromatic fused ring-typestructure; and a cyclic structural unit B linked to the unit A by asingle bond, the organic semiconductor material having a unit C as aside chain in at least either one of the unit A and the unit B,

the material exhibiting a phase other than N phase, SmA phase and SmCphase.

According to the knowledge of the present inventors, the reason why theorganic semiconductor material according to the present inventionexhibits a preferred characteristic may be presumed as follows.

In general, the liquid crystal substance may include a high-molecularweight liquid crystal and a low-molecular weight liquid crystal. In thecase of the high-molecular weight liquid crystal, the liquid crystalphase may generally has a high viscosity and therefore, is less liableto cause ionic conduction. On the other hand, in the case of thelow-molecular weight liquid crystal, when an ionized impurity ispresent, ionic conduction may tend to be induced in a low-order liquidcrystal phase having a strong liquid property, such as nematic phase (Nphase), smectic A phase (SmA phase; hereinafter, abbreviated in the samemanner) and SmC phase. The “ionized impurity” as used herein refers toan ionization product wherein ions are produced by the dissociation ofan ionic impurity; or an ionization product which is produced by thephotoionization or charge trapping of an electrically active impuritycapable of becoming a charge trap (that is, an impurity in which theHOMO level, the LUMO level or both of these levels have a level betweenthe HOMO and LUMO levels of the liquid crystal substance) (see, forexample, M. Funahashi and J. Hanna, Impurity effect on charge carriertransport in smectic liquid crystals, Chem. Phys. Lett., 397, 319-323(2004); H. Ahn, A. Ohno, and J. Hanna, Detection of Trace Amount ofImpurity in Smectic Liquid Crystals, Jpn. J. Appl. Phys., Vol. 44, No.6A, 2005, pp. 3764-37687).

When a liquid crystal thin film of a low-molecular weight liquid crystalsubstance is utilized as an organic semiconductor, in the case ofabove-described nematic phase having no ordered molecular orientation(or ordered alignment) of molecules, or in a smectic liquid crystalsubstance forming a molecularly-ordered condensed layer, because of thehigh flowability in the SmA phase or SmC phase having no positionalorientation of molecules in the molecular layer, the ionic conductionmay readily be induced in such a phase. Accordingly, there is causes aserious problem when these substances are used as an organicsemiconductor. On the other hand, in the case of the “other than Nphase, SmA phase and SmC phase” having a molecular orientation ofmolecules in the molecular layer, that is, a highly-ordered smecticphase (e.g., SmB, SmB_(cryst), SmI, SmF, SmE, SmJ, SmG, SmK, SmH, etc.),may have a property of hardly inducing ionic conduction (i.e., aproperty advantageous to the use thereof as an organic semiconductor).Further, these phases may generally be high in the molecular orientationorder and therefore, may exhibit a high mobility, as compared with thatof a low-order liquid crystal phase (see, H. Ahn, A. Ohno, and J. Hanna,“Impurity effects on charge carrier transport in various mesophases ofsmectic liquid crystal”, J. Appl. Phys., 102, 093718 (2007)).

In addition, past studies on the charge transport characteristics in aliquid crystal phase of various liquid crystal substances have reportedthat, in a liquid crystal substance having the same core structure, ahigher-order liquid crystal phase having a highly ordered molecularalignment in the smectic phase may exhibit a higher mobility. From thepoint of view of not only suppressing ionic conduction but alsorealizing a high mobility, a liquid crystal substance exhibiting ahighly-ordered smectic phase may be useful as an organic semiconductor.

On the other hand, in the case of using a liquid crystal substance as anorganic semiconductor in the form of a crystal thin film, a liquidcrystal substance allowing a low-order liquid crystal (N phase, SmAphase or SmC phase) with a strong liquid property which appears in atemperature region immediately above a crystal phase, may pose a seriousproblem such that, when a device is heated to a temperature higher thanthe temperature at which the above-described liquid crystal phaseappears, the device is damaged by the heat. On the contrary, in the caseof a liquid crystal substance capable of developing a higher-ordersmectic phase having a highly-ordered molecular alignment in themolecular layer, even when a device is heated to a liquid crystaltemperature, due to low flowability, the device is less liable to bedamaged. Therefore, even when a crystal thin film of a liquid crystalsubstance is applied to an electronic device as an organicsemiconductor, a liquid crystal substance exhibiting a high-order liquidcrystal phase may be required (however, just for this case, a substanceexhibiting a metastable crystal phase but not a liquid crystal phase mayalso be used). In other words, a liquid crystal material can suitably beused in the present invention, as long as the liquid crystal substanceis a substance exhibiting a metastable phase, or a liquid crystalsubstance exhibiting a crystal phase except for a low-order liquidcrystal phase (N phase, SmA phase or SmC phase) with a strong liquidproperty.

In general, in the case of a substance exhibiting a plurality of liquidcrystal phases or mesophases, it is well known that the molecularalignment of a liquid crystal phase is ordered along with a drop in thetemperature, and while the liquid crystal substance develops a low-orderliquid crystal phase (N phase, SmA phase or SmC phase) with a strongliquid property in a high temperature region, a high order liquidcrystal phase or a metastable crystal phase each having a highestorientation order is developed in a temperature region adjacent to acrystal phase temperature. In the case of using a liquid crystal phasethin film as an organic semiconductor material, a phase except for theabove-described low-order liquid crystal phase having a strong liquidproperty can be used in principle as an organic semiconductor.Accordingly, the condensed phase appearing in a temperature regionadjacent to a crystal phase may be sufficient, if it is not a low-orderliquid crystal phase having a strong liquid property (N phase, SmA phaseor SmC phase). In the case of a liquid crystal substance allowing forthe appearance of, in addition to a low-order liquid crystal phase (Nphase, SmA phase or SmC phase) having a strong liquid property, otherhigh-order liquid crystal phases, the low-order liquid crystal phase hasa strong liquid property and accordingly, the molecular alignmentcontrol is facilitated therein, as compared with that in the case of thehigh-order liquid crystal phase, molecules may be oriented in thelow-order liquid crystal phase and then transferred to the high-orderliquid crystal phase, to thereby obtain a liquid crystal thin film whichhas been reduced in the fluctuation of molecular alignment as well as inthe orientational defect can be obtained. Therefore, in such a case, animprovement in the quality of a liquid crystal thin film or a crystalthin film can be promised.

According to the present invention, an organic semiconductor materialexhibiting not only a liquid crystallinity but also a high electronmobility can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram showing one example of the basic conceptaccording to the present invention. FIG. 1B is a more detailed conceptof FIG. 1A.

FIG. 2 is an example of the polarizing micrograph (scale: the horizontalside is about 1 mm) showing a black linear structure or a texture (thatis, a crack or a void generated in the crystal), which may appear inassociation with crystallization.

FIG. 3 is an example of the polarizing micrograph showing a typicalSchlieren texture in a nematic phase.

FIG. 4 is an example of the polarizing micrograph (scale: the horizontalside is about 250 μm) showing a typical Fan-like texture seen in the SmAor SmC phase.

FIG. 5 is a graph showing one example of the TOF waveform for thecompound of Comp. No. 9.

FIG. 6 is a graph showing one example of the TOF waveform for thecompound of Comp. No. 9.

FIG. 7 is a graph showing one example of the TOF waveform for thecompound of Comp. No. 10.

FIG. 8 is a graph showing one example of the TOF waveform for thecompound of Comp. No. 20.

FIG. 9 is a graph showing one example of the TOF waveform for thecompound of Comp. No. 28.

FIG. 10 is a schematic cross-sectional view showing one example of theTFT device formed in Examples according to the present invention. In thefigure, reference numeral (a) denotes a source electrode, (b) a drainelectrode, (c) an organic semiconductor layer, (d) a gate insulatingfilm, and (e) a gate electrode.

FIG. 11 is a graph showing one example of the typical transmissionproperties of a transistor, which has been manufactured by using thecompound of Comp. No. 5.

FIG. 12 is a graph showing one example of the typical transmissionproperties of a transistor, which has been manufactured by using thecompound of Comp. No. 6.

FIG. 13 is a graph showing one example of the typical transmissionproperties of a transistor, which has been manufactured by using thecompound of Comp. No. 9.

FIG. 14 is a graph showing one example of the typical transmissionproperties of a transistor, which has been manufactured by using thecompound of Comp. No. 20.

FIG. 15 is a graph showing one example of the typical transmissionproperties of a transistor, which has been manufactured by using thecompound of Comp. No. 23.

FIG. 16 is a graph showing one example of the typical transmissionproperties of a transistor, which has been manufactured by using thecompound of Comp. No. 31.

FIG. 17 is (a) an example of the polarizing micrograph showing thepolarizing microscopic texture at room temperature, and (b) an exampleof the polarized optical microscopic image showing the polarizingmicroscopic texture of a phase in a high temperature region adjacent toa crystal phase, with respect to the compound of Comp. No. 5.

FIG. 18 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, With respect to the compound of Comp. No.6.

FIG. 19 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.7.

FIG. 20 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.8.

FIG. 21 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.9.

FIG. 22 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.10.

FIG. 23 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.11.

FIG. 24 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.12.

FIG. 25 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.13.

FIG. 26 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase., with respect to the compound of Comp. No.15

FIG. 27 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.19.

FIG. 28 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.20.

FIG. 29 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.21.

FIG. 30 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.22.

FIG. 31 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.23.

FIG. 32 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.24.

FIG. 33 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.27.

FIG. 34 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.28.

FIG. 35 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.29.

FIG. 36 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.30.

FIG. 37 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.31.

FIG. 38 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.49.

FIG. 39 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.50.

FIG. 40 is (a) an example of the polarized optical microscopic imagewhen slowly cooled and (b) an example of the polarized opticalmicroscopic image when rapidly cooled, from the isotropic phase, withrespect to the compound of Comp. No. 51.

FIG. 41 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.52.

FIG. 42 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.53.

FIG. 43 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.54.

FIG. 44 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.55.

FIG. 45 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.56.

FIG. 46 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.57.

FIG. 47 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.58.

FIG. 48 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.Comp. No. 59.

FIG. 49 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.60.

FIG. 50 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.61.

FIG. 51 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.62.

FIG. 52 is (a) an example of the polarized optical microscopic imageshowing the polarizing microscopic texture at room temperature and (b)an example of the polarized optical microscopic image showing thepolarizing microscopic texture of a phase in a high temperature regionadjacent to a crystal phase, with respect to the compound of Comp. No.63.

FIG. 53 is a graph which has been obtained by plotting the results in acase where an FET manufactured in Examples is subject to a heat stressat a predetermined temperature (shown on the abscissa) for 5 minutes andreturned to room temperature, and after the measurement of the FETproperties, the mobility (ordinate) is determined.

MODES FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in more detail byreferring to the accompanying drawings, as desired. In the followingdescription, the “parts” and “%” denoting quantitative ratios orproportions are based on mass, unless otherwise noted specifically.

(Organic Semiconductor Material)

The organic semiconductor material according to the present invention isan organic semiconductor material comprising at least a chargetransporting molecular unit A having an aromatic fused ring structure;and a cyclic structural unit B which is linked to the above unit A by asingle bond, and having an aliphatic side chain in at least one of theunits A and B. The organic semiconductor material according to thepresent invention is characterized in that it exhibits a liquid crystalphase other than N phase, SmA phase, and SmC phase.

(Predetermined Liquid Crystal Phase)

In the present invention, the “liquid crystal phase other than N phase,SmA phase, and SmC phase” stated above may preferably be a liquidcrystal phase selected from the group consisting of: SmB, SmB_(cryst),SmI, SmF, SmE, SmJ, SmG, SmK and SmH. The reason therefor may be becausewhen a liquid crystal phase of the liquid crystal substance according tothe present invention is used as an organic semiconductor, as describedhereinabove, this liquid crystal phase has low flowability (or fluidity)and therefore, is less liable to induce ionic conduction and further,due to the highly molecular alignment therein, a high mobility can bepromised in the liquid crystal phase. In addition, the reason may bebecause when a liquid crystal phase of the liquid crystal substanceaccording to the present invention is used as an organic semiconductor,this liquid crystal phase is low in the flowability as compared withthat of N phase, SmA phase, and SmC phase, and accordingly such a deviseis less liable to be damaged, even when a transition to a liquid crystalphase occurs due to a rise in the temperature. In a case where thedevelopment of a liquid crystal phase is seen only in a temperaturedecreasing process, when once crystallized, the crystal temperatureregion (or range) is broadened, and this is advantageous to theapplication thereof in the form of a crystal phase. The presentinvention is characterized in that in the temperature decreasing (orcooling) process, the “phase except for N phase, SmA phase, and SmCphase” is SmB_(cryst), SmE, SmF, SmI, SmJ, SmG, SmK or SmH.

Further, among the “liquid crystal phases except for SmA phase, and SmCphase”, SmE and SmG which are a higher-order Sm phase may be preferredas a liquid crystal phase appearing in a temperature region adjacent tothe crystal phase, when the temperature of the organic semiconductormaterial is raised from the crystal phase. Furthermore, in the case of aliquid crystal substance allowing for the appearance of other highlyordered liquid crystal phases, in addition to a low-order liquid crystalphase (N phase, SmA phase or SmC phase) having a strong liquid property,the low-order liquid crystal phase has a strong liquid property andaccordingly, the molecular alignment control is facilitated therein ascompared with that in the case of the highly ordered liquid crystalphase. Therefore, when molecules are oriented in advance in thelow-order liquid crystal phase and then are transferred to the highlyordered liquid crystal phase, a liquid crystal thin film which has beenreduced in the fluctuation of molecular alignment as well as in theorientational defect can be obtained and accordingly, an improvement inthe quality of a liquid crystal thin film or a crystal thin film can berealized.

In the case of using a liquid crystal substance as an organicsemiconductor, the operating temperature which is required for a deviceusing such a substance may usually be from −20° C. to 80° C. andtherefore, in the present invention, the temperature region in which the“phase except for N phase, SmA phase, and SmC phase” appears should be−20° C. or higher. Further, in a case where a crystal phase of theliquid crystal substance according to the present invention is used asan organic semiconductor, it may be effective for the qualityimprovement to utilize a thin film in the liquid crystal state (i.e., aliquid crystalline thin film) as a precursor at the production of acrystalline thin film. For this reason, in consideration of thesimplicity of the process and easiness in the selection of thesubstrate, the temperature at which a liquid crystal phase of the liquidcrystal substance appears may preferably be 200° C. or less.

(Preferred Charge Transporting Molecular Unit A)

In an organic semiconductor, the molecular moiety thereof participatingin the charge transport may be a conjugated π-electron system comprisingan aromatic ring or the like, and a larger size of the conjugatedπ-electron system may generally be advantageous to the charge transport.However, if the size of the π-electron system becomes large, thesolubility thereof in an organic solvent may be reduced and further,result in a high melting point, and there may be posed a problem suchthat the process at the time of the synthesis thereof or the use thereofas an organic semiconductor may tend to be difficult. Therefore, thenumber of rings constituting a fused ring of the charge transportingmolecular unit may preferably be from 3 to 5. The charge transportingmolecular unit A may contain a heterocyclic ring. Each of the ringsconstituting the fused ring may preferably have a carbon number of 5 or6 (that is, a 5- or 6-membered ring) in view of the convenience ofsynthesis thereof.

The heterocyclic ring constituting the charge transporting molecularunit A may also preferably be a 5- or 6-membered ring. The number ofheterocyclic rings may not be particularly limited, but may preferablybe the following number.

<Number of Rings of Unit A> <Number of Heterocyclic Rings> 3 1 4 1 to 25 1 to 3 (particularly 1 to 2)

In order to develop a highly ordered liquid crystal phase, a compoundconstituting the unit A may selected in consideration of its meltingpoint as a measure, because the melting point may be indicative of thecohesive energy of the compound. A compound having a high melting pointmay be a compound exerting a strong interaction between moleculesthereof at the time of the aggregation (or condensation) thereof, and isliable to undergo crystallization, whereby it is convenient to inducethe development of a highly ordered liquid crystal phase. Accordingly,the melting point of the compound constituting the unit A (**i.e., thecompound constituting the unit A, in a case where the unit B and theunit C are not linked to the unit A**) may preferably be 120° C. ormore, more preferably 150° C. or more, still more preferably 180° C. ormore, yet still more preferably 200° C. or more. If the melting point is120° C. or less, a low-order liquid crystal phase is liable to bedeveloped and this may not be preferred.

Hereinbelow, the compound constituting the unit A will be described inmore detail by referring to examples.

In a case where the target compound is Comp. No. 22, the pertinentcompound constituting the unit A may be the following compound, wherethe single bond linking to the unit B is eliminated, and a hydrogen atomis substituted therefor on the position of the following unit A, inwhich the single bond has been linked.

That is, in this example, the compound constituting the unit A isbenzothieno[3,2-b][1]benzothiophene, and the melting point of thebenzothieno[3,2-b][1]benzothiophene may be the melting point of thecompound constituting the unit A.

In this example, a single bond has been present between the unit A andthe unit B. However, even when a single bond is formed with the unit C,the melting point of the compound constituting the unit A may bespecified in the same manner.

The number of repetitions of the unit A may be 1 or may also be 2.

(Preferred Cyclic Structural Unit B)

In the present invention, the unit B may be “another structure” part forallowing freedom of the flip-flop movement. The unit B may preferably bean aromatic fused ring or an alicyclic molecular structure, which islinked to the charge transporting unit A by a single bond. The number ofrings **constituting the unit B** may preferably be from 1 to 5 (morepreferably, 3 or less, particularly preferably from 1 to 2).

The number of rings constituting the unit B may not be particularlylimited, but assuming that the number of the rings constituting the unitA is represented by “NA” and the number of the rings constituting theunit B is “NB”, NA≥NB may be preferred. More specifically, the number ofrings constituting the unit B may preferably be the following number.

<Number of Rings of Unit A> <Number of Rings of Unit B> 3 1 to 3,further 1 to 2 (particularly 1) 4 1 to 4, further 1 to 3 (particularly 1to 2) 5 1 to 5, further 1 to 4 (particularly 1 to 3)

The unit B may also contain a heterocyclic ring. The heterocyclic ringmay preferably be a 5- or 6-membered ring.

Further, the unit B may preferably be, for example, an aromaticcompound, an aromatic fused-ring compound, of which specific examplesmay be recited below, a cycloalkane, a cycloalkene, or an alicyclicsaturated compound. In the case of the cycloalkene, cyclopentene whichmay have higher planarity may be more preferred as compared withcyclohexene.

(Single Bond)

In the present invention, the unit A and the unit B should be directlylinked by a single bond.

(Unit C)

The unit C may be linked, for example, to the unit A and/or the unit B.From the view of broadening the crystal temperature region to be used asa crystalline thin film, this unit may preferably be linked to “eitherone” of the unit A and the unit B. The unit C may preferably be acompound having a linear structure, such as a hydrocarbon orheteroatom-containing saturated compound, more preferably a hydrocarbonhaving a carbon number of 2 to 20 or a group represented by formula (I):

[Chemical Formula 3]—(CH₂)_(n)—X—(CH₂)_(m)—CH₃  (1)

(wherein X represents S, O or NH, m is an integer of 0 to 17, and n isan integer of 2 or more).

With respect to the unit C, which is present on at least one of the unitA and unit B, as a side chain, in the cyclic structure (that is, A or B)to which the unit C is bonded, it is preferred that the position of theunit C is one capable of providing an organic semiconductor materialhaving a rod-like molecular shape, at which the cyclic structure islinked or condensed to the other cyclic structure (that is, B or A).Specific examples of the linking position may be those as shown in thestructures exemplified in Tables 1 to 8, and 15 appearing hereinafter.

In the description of the linking position of the unit C by referring tospecific compounds to be used for the organic semiconductor materialaccording to the present invention, for example, in the case of thefollowing structural formula, the unit A isbenzothieno[3,2-b][1]benzothiophene, the unit B is a phenyl group, theunit C is C₁₀H₂₁, the cyclic compound D to which the unit C is bonded isbenzene, and the unit A: benzothieno[3,2-b][1]benzothiophene and theunit C: C₁₀H₂₁ is linked on the para-position of the benzene.

With respect to another compound according to the present inventionhaving another unit, the linking position can be shown in the samemanner.

In the case of linking two cyclic compounds by a single bond, when asubstituent or a sterically large structure is present in the vicinityof the linking position, the rotary motion about an axis of twocompounds may be inhibited or limited due to the interaction of thesubstituent or structure, and as a result, a fluctuation may begenerated in the conformation at the aggregation of molecules or thereorganization energy affecting the charge transfer rate betweenmolecules may be increased. Therefore, even when a liquid crystalsubstance having such a molecular structure may develop a highly orderedliquid crystal phase, it is possible that the charge transportproperties may be degraded in many cases.

As described above, the number of repetitions of the unit A may be 1 ormay be 2, but as in Comp. No. 58, the entire structure of the compoundmay be repeated and in this case, the number of repetitions may be 1 ormay also be 2.

(Point of Molecular Design)

In the present invention, the molecular design may preferably beperformed by taking into account the following points so as to realize aliquid crystal substance having high mobility.

(1) In the present invention, it may be important that in a molecularlyordered liquid crystal phase or crystal phase, as the factor governingthe charge transfer rate, the Transfer integral value of the π-electronsystem molecular unit called a core part participating in the chargetransport is large. In order to actually calculate this value by aquantum-chemical method, the calculation need to be performed bydetermining the specific molecular configuration between adjacentmolecules in the target molecular condensed state, but comparativelyspeaking, a molecular structure having a redundantly extended π-electronsystem may be advantageous against a fluctuation in the mutuallyrelative molecular positions.

That is, in the case of a smectic liquid crystal substance, a rod-likeπ-electron conjugated system having a somewhat large size may beselected for the charge transporting molecular unit comprising aπ-electron conjugated system for providing a charge transport site. Inthis case, without using a molecular unit where a plurality of smallaromatic rings such as benzene or thiophene are linked by a single bondto form a large π-electron conjugated system, which may be oftenemployed as a liquid crystal molecular structure, a molecular unithaving a large π-electron conjugated system formed by a fused ringstructure may be used. The number of rings in the fused ring maypreferably be 3 or more and may be realistically 5 or less, because ifthe number of rings is too large, the solubility for a solvent may bereduced.

That is, in the present invention, the aromatic π-electron conjugatedsystem fused ring structure may preferably be a structure where benzene,pyridine, pyrimidine, thiophene, thiazole, imidazole or furan isemployed as an aromatic ring structure and these rings are fused toprovide for a rod-like three-ring, four-ring or five-ring structure.

(2) In the present invention, a highly ordered liquid crystal phaseshould be developed so as to realize high mobility. It may generally beconsidered that in the smectic liquid crystal phase, as transfers to ahighly ordered liquid crystal phase from SmA phase or SmC phase havingno positional order in the molecular layer, the molecular motion of aliquid crystal molecule is sequentially frozen and in the most highlyordered SmE phase or SmG phase, a flip-flop movement (sometimes referredto as flapping motion) of a molecule finally remains.

In consideration of this point, a structure where the above-describedaromatic π-electron conjugated system fused ring structure is linked byat least another rigid structure unit through a single bond maypreferably be used for a main core structure constituting a liquidcrystal molecule. In this case, as the another rigid structure unitlinked, a structure having a number of rings equal to or smaller thanthe number of rings in the above-described aromatic π-electronconjugated system fused ring structure may be selected, and the numberof rings may be 1 or 2. Further, this structure may not necessarily be astructure comprising only an aromatic ring in a broad sense encompassinga heterocyclic ring but may be an alicyclic ring structure such ascyclohexane, cyclopentane or double bond-containing cyclohexene orcyclopentene.

(3) In the present invention, in order to develop smectic liquidcrystallinity, the basic design of a rod-like liquid crystal substancemay be to provide the substance with a structure where a flexiblehydrocarbon unit for imparting rod-like molecular shape anisotropy andliquid property is linked to the above-described rigid molecular unitcalled a core part and these units are basically arranged in a linearconfiguration.

In the present invention, a structure where at least another rigidstructure is linked to the above-described aromatic π-electronconjugated system fused ring structure through a single bond may comeunder the core part. It may be important for the linkage position of theunit C in the core part to give rod-like anisotropy as the wholemolecule. In this case, with respect to the position of the unit Clinked to the core part, the unit may be linked to either the unit A orthe unit B or to both thereof as long as the position in each unit islocated farther from the single bond linking the unit A and the unit B.As for the molecular shape after linking the unit C, it should be keptin mind that when the structure of the whole molecule has large bending,smectic phase may generally be less liable to be induced.

In this molecular design, a measure therefor may be given by thefluctuation range when rotating a molecule in the core part by using, asthe axis, a single bond between the unit C and the core part. Morespecifically, describing the fluctuation range by letting the angleformed between a straight line linking a carbon atom bonded by the unitC to a carbon or hetero atom located on the outermost side of the corepart of the unit A or unit B and kept from directly bonding to the unitC on rotating the molecule and the axis be θ, a structure where thefluctuation range θ is 90° or less, preferably 60° or less, morepreferably 30° or less, may be preferred, because development of aliquid crystal phase and elevation of the mobility can be achieved.

As another measure, a single bond between the unit A and the unit B anda single bond between the unit C and unit A or between the unit C andthe unit B may preferably be in alignment with or in parallel to eachother or the angle formed by those two single bonds may preferably be90° or more, more preferably 120° or more.

An example where θ is 30° or less and two single bonds are in alignmentmay be illustrated in (scheme 1) “a”; an example where θ is 30° or lessand two single bonds are in parallel may be illustrated in (scheme 1)“b”; an example where θ is from 30° to 60° and the angle formed by twosingle bonds is 120° may be illustrated in (scheme 2) “a”; an examplewhere θ is from 30° to 60° and the angle formed by two single bonds is120° or more may be illustrated in (scheme 2) “b”; an example where θ is30° or less and two single bonds are in parallel may be illustrated in(scheme 3) “a”; and an example where θ is 30° or less and two singlebonds are in alignment may be illustrated in (scheme 3) “b”.

In the case of developing a liquid crystal phase, a unit C having astructure containing a double bond or a triple bond or containing ahetero atom such as oxygen, sulfur and nitrogen may be further used.However, in view of mobility, the unit C may preferably be bondeddirectly to the core part without intervention of oxygen, sulfur,nitrogen or the like.

(Screening Method)

In the present invention, the compounds satisfying the above-describedmolecular design may be screened, if desired, for a substance capable ofdeveloping a highly-ordered smectic liquid crystal phase and useful asan organic semiconductor. In this screening, it may be preferred toselect, fundamentally, a compound capable of developing a highly-orderedsmectic phase when using a liquid crystal phase as an organicsemiconductor, and a compound incapable of developing a low-order liquidcrystal phase adjacent to the crystal phase upon cooling from atemperature higher than the crystal phase temperature when using acrystal phase as an organic semiconductor. In this selection method, asubstance useful as an organic semiconductor material can be selected bymaking a judgment according to the later-described “Screening Method”.

FIG. 1A-1B show the basic concept according to the present invention.The structure shown in FIG. 1A may be called a core part in a liquidcrystal molecule, and a structure where a unit C (preferably a unithaving a carbon number of 3 or more) is linked to one side or both sidesof the core part to run in the molecular long axis direction of the corepart may be a basic design of the molecule in the present invention. Amore detailed concept of the concept of FIG. 1A may be shown in FIG. 1B.

(Charge Transporting Molecular Unit)

By using a molecular unit comprising an aromatic π-electron fused ringhaving a number of rings of 3 or more as the charge transportingmolecular unit corresponding to the core part in a liquid crystalmolecule, redundancy of the transfer integral for fluctuation of themolecular position can be ensured and similarly, by employing not amolecular unit of a π-electron conjugated system formed by linking aplurality of benzenes, thiophenes or the like by a single bond but amolecular unit having a fused ring structure, the molecular conformationmay be fixed, offering promise of increase in the transfer integral, andthis may be useful for enhancing the mobility.

On the other hand, even when a charge transporting molecular unit havinga large fused ring structure is employed as the core part, a substancewhere a hydrocarbon chain is directly linked to the core part as in, forexample, dialkylpentacene or dialkylbenzothienobenzothiophene cannotbring about stabilization of a liquid crystal phase and in general, maynot develop a liquid crystal phase or even if a liquid crystal phase isdeveloped, may develop only a low-order liquid crystal phase such as SmAphase (literatures: Liquid Crystal, Vol. 34, No. 9 (2007), 1001-1007;Liquid Crystal, Vol. 30. No. 5 (2003), 603-610). Therefore, highmobility in a liquid phase cannot be realized merely by using a largefused ring structure for the charge transporting molecular unit. Onlywhen a molecular structure in which another structural unit for allowingfreedom of the flip-flop movement (or motion) of a molecular is, asshown in the figure, linked to the charge transporting molecular unit isemployed for the core part, development of a highly ordered liquidcrystal phase and realization of high mobility in a liquid crystal phasemay be promised.

A hydrocarbon chain may be linked to such a structure (core part) inwhich another rigid structural unit is linked to the charge transportingmolecular unit, so as to impart rod-like anisotropy in molecular shapeand liquid property to a molecule, whereby development of a liquidcrystal phase can be induced with high probability. In the case oflinking a hydrocarbon chain, two hydrocarbon chains may generally belinked, but even when one hydrocarbon chain is linked, a liquid crystalphase may be often developed. In this case, the temperature region inwhich a liquid crystal phase appears may generally be different in thetemperature decreasing (or cooling) process and the temperature rising(or heating) process. This may be useful in allowing the temperatureregion of a liquid crystal phase to generally extend to a lowtemperature in the temperature decreasing process and conversely,allowing a crystal phase to extend to a high temperature region in thetemperature rising process. This property may imply that in the case ofutilizing a polycrystalline thin film of a liquid crystal substance asan organic semiconductor, a liquid crystalline thin film can be producedat a lower temperature when producing the polycrystalline thin film byusing a liquid crystalline thin film (thin film in a liquid crystalphase state) as a precursor, and may be advantageous in that the processis more facilitated. Further, extending a liquid crystal phasetemperature to a high temperature region in the temperature risingprocess may imply that the thermal stability of the producedpolycrystalline film is enhanced, and this may be convenient as amaterial. On the other hand, when two hydrocarbon chains are attached,the developed liquid crystal phase may be stabilized, and this may beconvenient for application to a device or the like using a liquidcrystal phase.

In a case where a substance is synthesized based on the above-describedbasic molecular design, the utility according to the present inventionof the substance may be taken advantage of by selecting, fundamentally,a substance capable of developing a highly-ordered smectic phase whenusing a liquid crystal phase as an organic semiconductor, and asubstance insusceptible to formation of a crack or a void in thecrystalline thin film and incapable of developing a low-order liquidcrystal phase adjacent to the crystal phase upon cooling from atemperature higher than the crystal phase temperature when using acrystal phase as an organic semiconductor. In other words, the judgmentmay be made based on whether a liquid crystal phase except for a nematicphase, SmA phase, and SmC phase is developed in a temperature regionadjacent to a crystal phase when using a liquid crystal phase as anorganic semiconductor and whether a crack or a void is hardly formedupon cooling from a temperature higher than the crystal phasetemperature and resulting occurrence of transition to a crystal phasewhen using a crystal phase as an organic semiconductor.

(Screening Method)

The judgment above can easily be made by the screening method (judgingmethod). For details of respective measurement methods used in thisscreening method, the following literatures may be referred to, ifdesired.

Literature A: “Henko Kenbikyo no Tsukaikata (How to Use PolarizingMicroscope)”, Jikken Kagaku-Kou (Experimental Chemistry Course), 4thed., Vol. 1, Maruzene, pp. 429-435

Literature B: “Ekisho Zairyo no Hyoka (Evaluation of Liquid CrystalMaterials)”, Jikken Kagaku Kouza (Experimental Chemistry Course), 5thed., Vol. 27, pp. 295-300, Maruzene

-   -   : Ekisho Kagaku Jikken Nyumon (Manual of Liquid Crystal Science        Experiments), compiled by The Japanese Liquid Crystal Society,        published by Sigma Shuppan

(S1) The isolated test substance may be purified by columnchromatography and recrystallization and thereafter, it may be confirmedby silica gel thin-layer chromatography that the test substance exhibitsa single spot (that is, not a mixture).

(S2) A sample heated into an isotropic phase may be injected, byutilizing a capillary phenomenon, in a 15 μm-thick cell formed bylaminating slide glasses through a spacer. The cell may be once heatedto an isotropic phase temperature, and the texture may be observed by apolarizing microscope to confirm that a dark field of view is notprovided in a temperature region lower than an isotropic phase. Thisrefers to that the molecular long axis is horizontally oriented withrespect to the substrate, and may become a requirement necessary for thesubsequent texture observations.

(S3) While cooling the cell at an appropriate temperature drop rate, forexample, at a rate of about 5° C./min, the texture may be observed bythe microscope. At this time, if the cooling rate is too fast, thestructure formed may become small to make a detailed observationdifficult, and therefore, the conditions for obtaining a structure sizeof 50 μm or more in which the structure is easily observed, may be setby again raising the temperature to an isotropic phase.

(S4) While cooling from an isotropic phase to room temperature (20° C.)under the conditions set in the item (S3) above, the texture may beobserved. When the sample is crystallized in the cell during thisprocess, a crack or a void may be generated in association withcontraction of the lattice, and a black line or a region having acertain size may appear in the observed texture. When an air isentrained at the time of injecting the sample, the same black region(generally, round) may be locally produced, but a black line or regionproduced by crystallization may distributedly appear in the structure orboundary and therefore, can easily be distinguished. Such a black lineor region can easily be discriminated from other structures seen in thetexture, because even when a polarizer and an analyzer are rotated,disappearance or change in color may not be observed (see, FIG. 2). Thetemperature at which this texture appears may be taken as acrystallization temperature, and it may be confirmed that the textureappearing in a temperature region higher than the temperature above isnot a nematic phase, SmA phase or SmC phase. In a case where the sampleexhibits a nematic phase, a characteristic Schlieren texture expressedas a bobbin-like texture (see, FIG. 3; a typical Schlieren texture) maybe observed, and In a case where the sample exhibits SmA phase or SmCphase, a characteristic texture called a fan-like texture, having a fanshape and having a uniform structure in the region (see, FIG. 4; atypical Fan-like texture) may be observed. Therefore, the texture caneasily be judged from its characteristic texture.

As a special case, in a substance undergoing transition from SmA phaseto SmB phase or from SmC phase to SmF or SmI phase, a change in thefield of view may be momentarily observed at a phase transitiontemperature, but almost no change may be sometimes observed in thetexture after phase transition and careful observation may be required,because the formed SmB phase, SmF phase or SmI phase texture may bemisidentified as SmA phase or SmC phase in some cases. In this case, itmay be important to pay attention to a momentary change in the field ofview, which may be observed at a phase transition temperature. In thecase of requiring this confirmation, when after confirming the number ofintermediate phases confirmed by DSC, X-ray diffraction is measured atrespective temperature regions and the presence or absence of a peak ina high-angle region (from 15 to 30° in the judgment of θ-2θ)characteristic of each phase is confirmed, the SmA phase, and SmC phase(both have no peak) can easily be discriminated from the SmB phase, SmFphase and SmI phase (all have a peak).

(S5) A substance in which a black structure is not seen by the textureobservation under a polarizing microscope at room temperature (20° C.)may be usable as an organic semiconductor material, and irrespective ofa highly ordered liquid crystal phase or a crystal phase (including ametastable crystal phase), this substance may be dealt with as asubstance in the scope of the present invention.

From the point of view of applying the organic semiconductor materialaccording to the present invention to a device, the HOMO and LUMO energylevels of the core part may be further important. In general, as for theHOMO level of an organic semiconductor, a test substance may bedissolved in an organic solvent such as dehydrated dichloromethane tohave a concentration of 1 to 10 mmol/L, about 0.2 mol/L of a supportingelectrolyte such as tetrabutylammonium salt may be added, a workingelectrode such as Pt, an opposite electrode such as Pt and a referenceelectrode such as Ag/AgCl may be inserted into the solution above, a CVcurve may be drawn by performing sweeping at a rate of about 50 mV/secby means of a potentiostat, and from the difference between the peakpotential and a potential of a known substance such as ferrocene, whichmay serve as the benchmark, the HOMO level and LUMO level may beestimated. In a case where the HOMO level or LUMO level deviates fromthe potential window of the organic solvent, the HOMO level or LUMOlevel can be estimated by calculating the HOMO-LUMO level from theabsorption edge of an ultraviolet-visible absorption spectrum andsubtracting it from the level that could be measured. For this method,J. Pommerehne, H. Vestweber, W. Guss, R. F. Mahrt, H. Bassler, M.Porsch, and J. Daub, Adv. Mater., 7, 551 (1995) may be referred to.

In general, the HOMO and LUMO levels of an organic semiconductormaterial may be indicative of electrical contact with an anode and acathode, respectively, and should be taken care of, because the chargeinjection may be limited by the size of energy barrier dependent on thedifference from the work function of an electrode material. As for thework function of a metal, for example, those of substances which areoften used as an electrode may be silver (Ag): 4.0 eV, aluminum (Al):4.28 eV, gold (Au): 5.1 eV, calcium (Ca): 2.87 eV, chromium (Cr): 4.5eV, copper (Cu): 4.65 eV, magnesium (Mg): 3.66 eV, molybdenum (Mo): 4.6eV, platinum (Pt): 5.65 eV, indium tin oxide (ITO): 4.35 to 4.75 eV, andzinc oxide (ZnO): 4.68 eV. From the above-described view, the differencein the work function between the organic semiconductor material and theelectrode substance may preferably be 1 eV or less, more preferably 0.8eV or less, still more preferably 0.6 eV or less. For the work functionof a metal, the following literature may be referred to, if desired.

Literature D: Kagaku Binran (Handbook of Chemistry), Basic Edition,revised 5th ed., II-608-610, 14.1 b Work Function (Maruzen) (2004)

The size of the conjugated π-electron system of the core part may affectthe HOMO and LUMO energy levels, and therefore, the size of theconjugated system may be used as a reference when selecting thematerial. Further, introduction of a hetero atom into the core part maybe effective as a method for changing the HOMO or LUMO energy level.

(Examples of Preferred Charge Transporting Molecular Unit A)

Examples of the “charge transporting molecular unit A” suitably usablein the present invention are illustrated below. X represents S, O or NH.

(Examples of Preferred Cyclic Structural Unit B)

Examples of the “cyclic structural unit B” suitably usable in thepresent invention are illustrated below. The unit B may be the same asthe unit A.

(Examples of Preferred Single Bond)

The “single bond” for linking the units A and B, which is suitablyusable in the present invention, may be selected such that out ofcarbons constituting the cyclic structures of the unit A and the unit B,carbons in the molecular long axis direction are linked to take arod-like shape by the whole molecule. That is, in the present invention,a carbon constituting the unit A and a carbon constituting the unit Bare linked directly by a “single bond”.

(Examples of Preferred Combination of Unit A and Unit B)

Examples of the “combination of unit A and unit B” (linked according tothose described above) suitably usable in the present invention areillustrated below.

(Preferred Unit C)

As the unit C, either a linear unit or a branched unit may be usable,but a linear unit may be more preferred. The carbon number of the unit Cmay preferably be 2 or more. This carbon number may be more preferablyfrom 3 to 20. Increase in the carbon number may generally lead toreduction in the liquid crystal phase temperature and may be convenientparticularly when using a liquid crystal phase as an organicsemiconductor. However, on the other hand, if the carbon number is toolong, the solubility for an organic solvent may be reduced andaccordingly, the process suitability may be sometimes impaired. In thecase of using a carbon number, when a structure containing oxygen,sulfur or nitrogen in the unit C is used, this may be effective inimproving the solubility. At this time, a structure where the oxygen,sulfur or nitrogen atom is not directly linked o the unit A or unit Bmay be preferred in view of mobility, and a structure where linkage tothe unit A or unit B is mediated by two or more carbons and then,oxygen, sulfur or nitrogen is linked may be preferred in view ofchemical stability. Among examples above, specific examples of the unitA, unit B and unit C which are particularly suitable for attaining theobject of the present invention may be illustrated below.

<Unit A>

The compound of the unit A recited above may have a commonly known andused substituent that is substitutable on the unit A. Such a substituentmay not be limited as long as it does not interfere with attaining theobject of the present invention, but preferred substituents include thefollowings:

an alkyl group, a halogen atom, an aliphatic compound having aheteroatom such as oxygen atom, nitrogen atom and sulfur atom, analkenyl group, an alkynyl group, and an aromatic compound as asubstituent, such as thiophene, thienothiophene, benzothiophene,benzene, naphthalene, biphenyl fluorene, pyridine, imidazole,benzothiazole and furan.

<Unit B>

Thiophene, thienothiophene, benzothiophene, benzene, naphthalene,biphenyl, fluorene, pyridine, imidazole, benzothiazole, furan,cyclopentene, cyclohexene, tetrahydrofuran, tetrahydropyrane,tetrahydrothiophene, pyrrolidine, and piperidine.

The compound of the unit B recited above may have a commonly known andused substituent. Such a substituent may not be limited as long as itdoes not interfere with attaining the object of the present invention,but preferred substituents include the followings:

an alkyl group, a halogen atom, an aliphatic compound having aheteroatom such as oxygen atom, nitrogen atom and sulfur atom, analkenyl group, an alkynyl group, and an aromatic compound as asubstituent, such as thiophene, thienothiophene, benzothiophene,benzene, naphthalene, biphenyl fluorene, pyridine, imidazole,benzothiazole and furan.

Among others, cyclopentene, cyclohexene, tetrahydrofuran,tetrahydropyran, tetrahydrothiophene, pyrrolidine, piperidine and thelike may be preferred, because the mobility may be enhanced due toproviding planarity to the crystal structure of the compound.

<Unit C>

A linear alkyl group having a carbon number of 2 to 20,

(Confirmation of Mobility as Semiconductor)

By the experiment (Measurement of Transient Photocurrent byTime-of-flight method) in Example 41 described later, it can beconfirmed that the organic semiconductor material according to thepresent invention has mobility suitable for the action as asemiconductor. For details on the confirmation of mobility by thismethod, for example, the literature: Appl. Phys. Lett., 71, No. 5,602-604 (1997) may be referred to.

One of measures for usefulness when applying an organic semiconductor toa device may be mobility of the substance, because the properties of thedevice are limited by the mobility. Heretofore, in the case of anamorphous organic semiconductor, the mobility may be about 10⁻² cm²/Vsat highest and may generally be from 10⁻⁵ to 10⁻³ cm²/Vs. Accordingly, ahigh mobility exceeding 10⁻² cm²/Vs of a liquid crystal phase,

particularly, a mobility exceeding 0.1 cm²/Vs of a highly-orderedsmectic phase, can be hardly realized by an amorphous organicsemiconductor material, clearly revealing superiority of the liquidcrystal material.

A liquid crystalline substance may exhibit a crystal phase, similarly toa non-liquid crystal substance, and therefore, in using it as an organicsemiconductor, the liquid crystal substance can be of course used as anorganic semiconductor not only in a liquid crystal phase but also in acrystal phase. In general, the mobility in a liquid crystal phase may beoften higher by approximately from about half a digit (or an order) toone digit (or one order) than the mobility in a liquid crystal phase,and among other, in application to a transistor requiring high mobilityor application to a solar cell or the like requiring a large diffusionlength of a charge or an exciton, utilization of a crystal phase may beeffective.

(Confirmation of Semiconductor Device Operation)

The experiment (Measurement of Transient Photocurrent by Time-of-flightmethod) in Example 41 described later may involve observing thegeneration of a photocharge by light irradiation and the chargetransport, and this measurement system may correspond to realization ofa photosensor using an organic semiconductor material. Accordingly, itcan be confirmed by this measurement that the organic semiconductormaterial according to the present invention is usable for asemiconductor device operation. For details on confirmation of thesemiconductor device operation by this method, for example, theliterature: Appl. Phys. Lett., 74, No. 18, 2584-2586 (1999) may bereferred to.

Further, as demonstrated in Example 45, by manufacturing FET andevaluating the properties thereof, it can be confirmed that the organicsemiconductor material according to the present invention is usable asan organic transistor. For details on confirmation of the semiconductordevice operation by this method, for example, the literature: S. F.Nelsona, Y.-Y. Lin, D. J. Gundlach, and T. N. Jackson,Temperature-independent transport in high-mobility pentacenetransistors, Appl. Phys. Lett., 72, No. 15, 1854-1856 (1998) may bereferred to.

(Preferred Structure)

According to the molecular design by the present invention, a structureformed by linking, in the molecular long axis direction, a hydrocarbonchain unit having a carbon number of 3 or more to either one structurein a structure where a fused ring system having linked therein from 3 to5 aromatic rings in a rod-like manner (that is, substantially linearly)through a single bond is linked by at least another cyclic structure inthe molecular long axis direction of the fused ring system, may befundamentally preferred in the present invention.

As described above, the basis of the molecular design in the presentinvention may be a structure formed by linking, in the molecular longaxis direction, a hydrocarbon chain unit having a carbon number of 3 ormore to either one structure in a structure where a fused ring systemhaving linked therein from 3 to 5 aromatic rings in a rod-like manner islinked by at least another cyclic structure through a single bond in themolecular long axis direction of the fused ring system. This may beexemplified in Examples using, for example, the following substances(see, the Figure).

TABLE 1 COM5

COM6

COM7

COM8

COM9

TABLE 2 COM10

COM11

COM12

COM13

COM14

TABLE 3 COM15

COM16

COM17

COM18

COM19

TABLE 4 COM20

COM21

COM22

COM23

COM24

TABLE 5 COM25

COM26

COM27

COM28

TABLE 6 COM29

COM30

COM31

Further, in the group of compounds used in the present invention, themolecular design may be performed by appropriately combining theabove-described units A to C, and specific compounds may include thefollowings, but the group of compounds applicable in the presentinvention may be of course not limited thereto.

TABLE 7 COM32

COM33

COM34

COM35

COM36

COM37

COM38

COM39

COM40

COM41

TABLE 8 COM42

COM43

COM44

COM45

COM46

COM47

COM48

This group of compounds may be synthesized by referring to the followingreferences and synthesis examples described in Examples later.

For example, in the synthesis of Comp. No. 32, the preparation thereofmay be achieved in the same manner as in Example 20 by using, in placeof dodecanoic acid chloride in Example 20, a compound obtained bytreating a reaction product of 2-bromoacetic acid and decanol withthionyl chloride.

In the synthesis of Comp. No. 33, the preparation thereof may beachieved by introducing bromine into benzo[1,2-b:4,5-b′]dithiophene, andsubsequently reacting the resulting product with B(OH)₂ for providingthe unit A, and then subjecting the resulting compound to a couplingreaction with 2-bromo-7-hexylfluorene.

In the synthesis of Comp. No. 34, the preparation thereof may beachieved by synthesizing pentathienoacene for providing the unit Aaccording to the method described in Journal of American Chem. Soc.,127, 13281-13286, 2005, then monobrominating the unit A, and reactingthe resulting compound with groups corresponding to the units B and Cdescribed in Example 24.

In the synthesis of Comp. No. 35, the preparation thereof may beachieved by performing a coupling reaction in the same manner as inExample 20 by using, in place of dodecanoic acid chloride in Example 20,a compound obtained by treating a reaction product of 3-bromopropionicacid and dodecanol with thionyl chloride and further using, in place ofphenylboronic acid, a reaction product of bromopyridine andbispinacolate diborane.

In the synthesis of Comp. No. 36, the preparation thereof may beachieved by monobrominating benzo[b]thieno[2,3-d]thiophene for providingthe unit A and then reacting the resulting compound with groupscorresponding to the units B and C described in Example 24.

In the synthesis of Comp. No. 37, the preparation thereof may beachieved by synthesizing dibenzo[d,d′]thieno[3,2-b:4,5-b]dithiophene forproviding the unit A according to the method described in AdvancedMater., 19, 3008-3011, 2007, then brominating the unit A, and performinga coupling reaction in the same manner as in Example 20 by using, inplace of dodecanoic acid chloride in Example 20, a compound obtained bytreating nanodecanoic acid with thionyl chloride and further using, inplace of phenylboronic acid, a reaction product of bromopyridine andbispinacolate diborane.

In the synthesis of Comp. No. 38, the preparation thereof may beachieved by performing a coupling reaction in the same manner as inExample 20 by using, in place of dodecanoic acid chloride in Example 20,a compound obtained by treating eicosanoic acid with thionyl chlorideand further using, in place of phenylboronic acid, a reaction product ofbromobenzothiazole and bispinacolate diborane.

In the synthesis of Comp. No. 39, the preparation thereof may beachieved by synthesizing carbazole for providing the unit A according tothe method described in Tetrahedron, 67, 8248-8254, 2011, thenmonobrominating the unit A, and reacting the resulting compound withgroups corresponding to the units B and C described in Example 24.

In the synthesis of Comp. No. 40, the preparation thereof may beachieved by synthesizing dibenzo[d,d′]benzo[1,2-b:4,5-b]dithiophene forproviding the unit A according to the method described in Org. Lett., 9,4499-4502, 2007, then brominating the unit A, and performing a couplingreaction in the same manner as in Example 20 by using, in place ofdodecanoic acid chloride in Example 20, a compound obtained by treatinga reaction product of 6-bromohexanoic acid and hexanol with thionylchloride and further using, in place of phenylboronic acid, a reactionproduct of 3-bromofuran and bispinacolate diborane.

In the synthesis of Comp. No. 41, the preparation thereof may beachieved by monobrominating tetracene for providing the unit A and thenreacting the resulting compound with groups corresponding to the units Band C described in Example 24.

Comp. No. 42 to Comp. No. 48 may be further synthesized by the samemethod.

Further, the compounds of Comp. No. 32 to Comp. No. 48 may be confirmedto be in the group of compounds capable of solving the task of thepresent invention, by the method described in the literature recited inthe paragraph of Screening Method.

The materials used in Examples may be shown together in the Tablesbelow. In the Tables, respective signs have the following meanings.

(a) Chemical structural formula

(b) Phase transition behavior (cooling process)

*I: Isotropic phase

N: Nematic phase

SmA: Smectic A phase

SmC: Smectic C phase

SmE: Smectic E phase

SmG: Smectic G phase

SmX: Highly ordered smectic phase or metastable crystal

K: Crystal phase

TABLE 9 Compound (a) (b) COM5

I-(201° C.)-SmA-(195° C.)-SmE COM6

I-(202° C.)-SmA-(188° C.)-SmE-(107° C.)-K COM7

I-(200° C.)-SmA-(185° C.)-SmE-(100° C.)-K COM8

I-(201° C.)-SmA-(183° C.)-SmE-(93° C.)-K COM9

I-(198° C.)-SmA-(180° C.)-SmE-(102° C.)-K

TABLE 10 Compound (a) (b) COM10

I-(202° C.)-SmA-(188° C.)-SmE-(108° C.)-K COM11

I-(169° C.)-SmX-(115° C.)-K COM12

I-(235° C.)-SmA-(219° C.)-SmE-(71° C.)-K COM13

I-(237° C.)-SmX-(184° C.)-K COM14

I-(202° C.)-SmX-(191° C.)-K

TABLE 11 Compound (a) (b) COM15

I-(243° C.)-N-(223° C.)-SmA-(207° C.)-SmX-(194° C.)-K COM16

I-(231° C.)-N-(223° C.)-SmA-(200° C.)-SmE-(172° C.)-K COM17

I-(238° C.)-N-(227° C.)-SmA-(191° C.)-SmE-(165° C.)-K COM18

I-(224° C.)-SmA-(186° C.)-SmE-(166° C.)-K

TABLE 12 Compound (a) (b) COM19

I-(230° C.)-SmA-(188° C.)-SmE-(148° C.)-K COM20

I-(223° C.)-SmA-(182° C.)-SmE-(149° C.)-K COM21

I-(221° C.)-SmA-(179° C.)-SmE-(147° C.)-K COM22

I-(219° C.)-SmA-(178° C.)-SmE-(142° C.)-K COM23

I-(213° C.)-SmA-(174° C.)-SmE-(136° C.)-K

TABLE 13 Compound (a) (b) COM24

I-(223° C.)-SmA-(210° C.)-SmE-(90° C.)-K COM25

I-(194° C.)-SmA-(162° C.)-SmE-(141° C.)-K (temperature rising process)COM26

I-(260° C.)-SmX-(175° C.)-K COM27

I-(147° C.)-SmX-(134° C.)-K

TABLE 14 Compound (a) (b) COM28

I-(205° C.)-SmX-(58° C.)-K COM29

I-(155° C.)-SmX-(114° C.)-K COM30

I-(305° C.)-SmX-(229° C.)-K COM31

I-(249° C.)-SmC-(172° C.)-SmX-(100° C.)-K

TABLE 15 (a) (b) COM49

I-(264° C.)-SmA-(210° C.)-SmE COM50

I-(176° C.)-SmA-(152° C.)-SmE COM51

I-(91° C.)-SmX COM52

I-(254° C.)-SmA-(211° C.)-SmE- (81° C.)-K COM53

I-(213° C.)-SmA-(173° C.)-SmE COM54

I-(172° C.)-SmA-(163° C.)-SmE- (57° C.)-K COM55

I-(211° C.)-SmA-(185° C.)-SmE- (120° C.)-K COM56

I-(126° C.)-SmX-(51° C.)-K COM57

I-(272° C.)-SmA-(243° C.)-SmE- (200° C.)-K COM58

I-(311° C.)-N-(265° C.)-SmX- (214° C.)-K COM59

I-(215° C.)-SmA-(158° C.)-SmE- (98° C.)-K COM60

I-(272° C.)-SmA-(215° C.)-SmE COM61

I-(274° C.)-SmX COM62

I-(164° C.)-SmX-(128° C.)-K COM63

I-(174° C.)-SmX₁-(138° C.)-SmX₂- (112° C.)-K

EXAMPLES Example 1

The raw material [1][benzothieno[3,2-b][1]benzothiophene-2-amine wassynthesized by the method described in B. Kosata, V. Kozmik and J.Svoboda, Collect. Czech. Chem. Commun., Vol. 67, 645 (2002).

[1][Benzothieno[3,2-b][1]benzothiophene-2-amine (3.76 g, 0.014 mol) wasadded to a solution of hydrochloric acid (110 ml) and water (220 ml).This solution was cooled to 5° C. and then added dropwise to a solutionobtained by dissolving sodium nitrite (1.1 g, 0.016 mol) in water (66ml). The resulting reaction solution was stirred at 5° C. for 3.5 hours,and a solution obtained by dissolving potassium iodide (2.65 g, 0.016mol) in water (66 ml) was added dropwise thereto. The reactiontemperature was returned to room temperature, and the reaction solutionwas stirred for 16 hours. The precipitate in the reaction solution wascollected by filtration, washed with water and extracted withdichloromethane. After concentrating the solvent, the obtained residuewas purified by column chromatography to obtain 3.38 g (yield: 66%) of2-iodo[1][benzothieno[3,2-b][1]benzothiophene.

NMR (300 MHz, in CDCl₃): 8.26 (d, J=1.2 Hz, 1H), 7.92 (dd, J=0.9 Hz,J=5.7 Hz, 1H),

7.88 (dd, J=1.2 Hz, J=6.3 Hz, 1H), 7.74 (dd, J=1.2 Hz, J=6.3 Hz, 1H),7.62 (d, J=6.0 Hz, 1H),

7.51-7.41 (m, 2H).

Using the thus-synthesized 2-iodo[1][benzothieno[3,2-b][1]benzothiopheneas a raw material, the target compound was synthesized by a Suzukicoupling reaction using a corresponding boron compound. A general methodis described by using Comp. No. 9 as an example.

In an argon atmosphere, 2-iodo[1][benzothieno[3,2-b][1]benzothiophene(120 mg, 0.32 mmol),2-(5-octylthienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (130 mg,0.39 mol) and cesium carbonate (130 g, 0.40 mmol) were dissolved in1,2-dimethoxyethane/water (10 m/1 ml) and after addingtetrakis(triphenylphohsphine)palladium (23 mg, 0.02 mmol), the solutionwas heated with stirring at 95° C. for 19 hours. The reaction solutionwas concentrated and then extracted with chloroform, and the organiclayer was washed with water and dried over magnesium sulfate. Afterconcentrating under reduced pressure, the residue was purified by columnchromatography to obtain 70 mg (yield: 50%) of the compound of Comp. No.9.

¹H-NMR (300 MHz, CDCl₃, δ): 8.08 (d, J=1.2 Hz, 1H), 7.95 (dd, J=1.2 Hz,J=8.1 Hz, 1H),

7.88 (m, 1H), 7.84 (d, J=8.1 Hz, 1H), 7.67 (dd, J=1.2 Hz, J=8.4 Hz, 1H),7.46 (ddd, J=1.2 Hz,

J=7.2 Hz, J=8.4 Hz, 1H), 7.40 (ddd, J=1.2 Hz, J=7.2 Hz, J=8.4 Hz, 1H),7.22 (d, J=3.6 Hz, 1H),

6.79 (d, J=3.6 Hz, 1H), 2.84 (t, J=7.5 Hz, 2H), 1.75-1.70 (m, 2H),1.41-1.29 (m, 10H),

0.89 (t, J=6.6 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 21.

Example 2

From 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (150 mg, 0.41 mmol)and 2-(5-butylthienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (120mg, 0.45 mol), 60 mg (yield: 39%) of the compound of Comp. No. 5 wasobtained by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.07 (d, J=1.2 Hz, 1H), 7.93 (dd, J=1.2 Hz,J=8.1 Hz, 1H),

7.88 (m, 1H), 7.85 (d, J=8.1 Hz, 1H), 7.67 (dd, J=1.2 Hz, J=8.4 Hz, 1H),

7.46 (ddd, J=1.2 Hz, J=7.2 Hz, J=8.4 Hz, 1H), 7.40 (ddd, J=1.2 Hz, J=7.2Hz, J=8.4 Hz, 1H),

7.22 (d, J=3.6 Hz, 1H), 6.78 (d, J=3.6 Hz, 1H), 2.86 (t, J=7.5 Hz, 2H),1.77-1.67 (m, 2H),

1.50-1.41 (m, 2H), 0.99 (t, J=7.1 Hz, 3H).

This substance was subjected to by the screening method described inthis specification, so as to observe the texture thereof. The thusobtained observation results are shown in FIG. 17.

Example 3

From 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (130 mg, 0.35 mmol)and 2-(5-pentylthienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (110mg, 0.39 mol), 90 mg (yield: 65%) of the compound of Comp. No. 6 wasobtained by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.08 (d, J=1.2 Hz, 1H), 7.93 (dd, J=1.2 Hz,J=8.1 Hz, 1H),

7.89 (m, 1H), 7.85 (d, J=8.1 Hz, 1H), 7.67 (dd, J=1.2 Hz, J=8.4 Hz, 1H),

7.46 (ddd, J=1.2 Hz, J=7.2 Hz, J=8.4 Hz, 1H), 7.40 (ddd, J=1.2 Hz, J=7.2Hz, J=8.4 Hz, 1H),

7.22 (d, J=3.6 Hz, 1H), 6.78 (d, J=3.6 Hz, 1H), 2.85 (t, J=7.5 Hz, 2H),1.76-1.71 (m, 2H),

1.42-1.37 (m, 4H), 0.91 (t, J=7.0 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 17.

Example 4

From 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (80 mg, 0.22 mmol)and 2-(5-hexylthienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (71mg, 0.24 mol), 45 mg (yield: 51%) of the compound of Comp. No. 7 wasobtained by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.08 (d, J=1.2 Hz, 1H), 7.92 (dd, J=1.2 Hz,J=8.1 Hz, 1H),

7.88 (d, J=8.1 Hz, 1H), 7.84 (d, J=8.1 Hz, 1H), 7.66 (dd, J=1.2 Hz,J=8.4 Hz, 1H),

7.46 (ddd, J=1.2 Hz, J=7.8 Hz, J=8.4 Hz, 1H), 7.41 (ddd, J=1.2 Hz, J=7.8Hz, J=8.4 Hz, 1H),

7.24 (d, J=3.6 Hz, 1H), 6.79 (d, J=3.6 Hz, 1H), 2.84 (t, J=7.5 Hz, 2H),1.75-1.70 (m, 2H),

1.44-1.30 (m, 6H), 0.91 (t, J=6.0 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 19.

Example 5

From 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (130 mg, 0.35 mmol)and 2-(5-heptylthienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (120mg, 0.39 mol), 56 mg (yield: 38%) of the compound of Comp. No. 8 wasobtained by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.08 (d, J=1.2 Hz, 1H), 7.93 (dd, J=1.2 Hz,J=8.1 Hz, 1H),

7.89 (m, 1H), 7.85 (d, J=8.1 Hz, 1H), 7.65 (dd, J=1.2 Hz, J=8.4 Hz, 1H),7.46 (ddd, J=1.2 Hz,

J=7.2 Hz, J=8.4 Hz, 1H), 7.41 (ddd, J=1.2 Hz, J=7.2 Hz, J=8.4 Hz, 1H),7.22 (d, J=3.6 Hz, 1H),

6.78 (d, J=3.6 Hz, 1H), 2.85 (t, J=7.5 Hz, 2H), 1.75-1.68 (m, 2H),1.46-1.31 (m, 8H),

0.89 (t, J=7.0 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 20.

Example 6

Comp. No. 10 was synthesized by the following method.

The raw material 2-ethyl[1]benzothieno[3,2-b]benzothiophene wassynthesized by the method described in B. Kosata, V. Kozmik and J.Svoboda, Collect. Czech. Chem. Commun., Vol. 67, 645 (2002).

2-Ethyl[1]benzothieno[3,2-b]benzothiophene (550 mg, 2.0 mmol) wasdissolved in dichloromethane (40 ml) and after cooling to −45° C., adichloromethane (5 ml) solution of fuming nitric acid (250 mg, 4.0 mmol)was added dropwise thereto. The reaction solution was stirred at −45 to−30° C. for 40 minutes and then returned to room temperature. Thissolution was extracted with dichloromethane, washed with water and driedover magnesium sulfate. The solvent was removed by distillation toobtain a yellow solid substance (630 mg).

The obtained yellow solid substance (630 mg) was suspended in toluene(60 ml) and subsequently, iron powder (1.94 g, 34.8 mmol) was

added thereto. The resulting suspension was heated with stirring at 125°C. and to this reaction solution, a solution obtained by dissolvingammonium chloride (100 mg, 1.8 mmol) in water (1.6 ml) was addeddropwise. After the dropwise addition, the solution was heated withstirring for 1 hour, and the toluene layer was separated and dried overmagnesium sulfate. The solvent was removed by distillation under reducedpressure, and the residue was purified by column chromatography toobtain 470 mg (yield: 84%) of2-amino-7-ethyl[1]benzothieno[3,2-b]benzothiophene.

¹H-NMR (300 MHz, CDCl₃, δ): 7.70 (d, J=0.6 Hz. 1H), 7.69 (d, J=0.6 Hz.1H), 7.63 (d, J=8.4 Hz. 1H), 7.27 (m, 1H), 7.17 (d, J=2.0 Hz, 1H), 6.82(dd, J=2.0 Hz, J=8.4 Hz, 1H), 3.85 (bs, 2H),

2.79 (q, J=7.5 Hz, 2H), 1.32 (t, J=7.5 Hz, 3H).

Concentrated hydrochloric acid (11 ml) and water (22 ml) were added to2-amino-7-ethyl[1]benzothieno[3,2-b]benzothiophene (470 mg, 1.67 mmol),and the system was cooled to 5° C. To this solution, a solution obtainedby dissolving sodium nitrite (130 mg, 0.19 mmol) in water (7 ml) wasadded dropwise. The resulting solution was stirred at 5° C. for 1 hourand thereafter, a water (7 ml) solution of potassium iodide (300 mg,1.83 mmol) was added dropwise. The reaction solution was returned toroom temperature and stirred for 4 hours, and the reaction mixture wasextracted with chloroform, washed with water and dried over magnesiumsulfate. The solvent was removed by distillation under reduced pressure,and the residue was purified by column chromatography to obtain 400 mg(yield: 61%) of 2-iodo-7-ethyl[1]benzothieno[3,2-b]benzothiophene.

¹H-NMR (300 MHz, CDCl₃ δ): 8.23 (d, J=1.4 Hz, 1H), 7.78 (d, J=8.2 Hz,1H),

7.72 (dd, J=1.4, J=8.2 Hz, 1H), 7.73 (d, J=1.4 Hz, 1H), 7.62 (d, J=8.2Hz, 1H),

7.26 (dd, J=1.8 Hz, J=8.2 Hz, 1H), 2.82 (q, J=7.0 Hz, 2H), 0.93 (t,J=7.0 Hz, 3H).

In an argon atmosphere,2-iodo-7-ethyl[1]benzothieno[3,2-b]benzothiophene (200 mg, 0.50 mmol),2-(5-octylthienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (160 mg,0.51 mol) and cesium carbonate (170 mg, 0.51 mmol) were dissolved in1,2-dimethoxyethane/water (20 m/2 ml), andtetrakis(triphenylphosphine)palladium (29 mg, 0.025 mmol) was addedthereto. The system was stirred at 95° C. for 20 hours, and theresulting reaction solution was concentrated and then extracted withchloroform. The organic layer was washed with water and dried overmagnesium sulfate and after removing the solvent by distillation underreduced pressure, the residue was purified by column chromatography toobtain 70 mg (yield: 30%) of the compound of Comp. No. 10.

¹H-NMR (300 MHz, CDCl₃, δ): 8.05 (d, J=1.2 Hz, 1H), 7.79 (d, J=8.1 Hz,1H),

7.76 (d, J=8.1 Hz, 1H), 7.72 (d, J=0.6 Hz, 1H), 7.63 (dd, J=1.8 Hz,J=8.1 Hz, 1H), 7.23 (dd, J=1.8 Hz, J=8.1 Hz, 1H), 7.20 (d, J=3.6 Hz,1H), 6.77 (d, J=3.6 Hz, 1H), 2.85 (q, J=4.8 Hz, 2H), 2.79 (q, J=7.5 Hz,2H), 1.77-1.66 (m, 2H), 1.50-1.20 (m, 10H), 0.91 (t, J=4.8 Hz, 3H), 0.89(t, J=7.5 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 22.

Example 7

Copper bromide (5.74 g, 40 mmol) was added to a pyridine solution of2-iodo[1][benzothieno[3,2-b][1]benzothiophene (1.69 g, 4.6 mmol), andthe system was heated under reflux for 21 hours. Water (250 ml) wasadded to the reaction solution and subsequently, 20% sulfuric acid wasadded to adjust the pH to 7.0. Thereafter, the reaction solution wasextracted with dichloromethane, washed with water and dried overmagnesium sulfate. After concentrating under reduced pressure, theresidue was purified by column chromatography to obtain 1.45 g (yield:98%) of 2-bromo[1][benzothieno[3,2-b][1]benzothiophene.

NMR (300 MHz, in CDCl₃): 8.03 (d, J=1.5 Hz, 1H), 7.93-7.85 (m, 2H), 7.20(d, J=8.4 Hz, 1H),

7.54 (dd, J=1.8 Hz, J=8.4 Hz, 1H), 7.49-7.38 (m, 2H).

In an argon atmosphere, 2-bromo[1][benzothieno[3,2-b][1]benzothiophene(200 mg, 0.62 mmol),2-(4-octylthienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (260 mg,0.82 mol) and cesium carbonate (300 mg, 0.92 mmol) were dissolved indimethylformamide (1 ml), and tetrakis(triphenylphosphine) palladium (26mg, 0.02 mmol) was added thereto. The system was heated with stirring at95° C. for 19 hours, and the reaction solution was concentrated and thenextracted with chloroform. The organic layer was washed with water, anddried over magnesium sulfate. After concentrating under reducedpressure, the residue was purified by column chromatography to obtain185 mg (yield: 69%) of the compound of Comp. No. 11.

¹H-NMR (300 MHz, CDCl₃, δ): 8.12 (d, J=1.5 Hz, 1H), 7.92 (d, J=7.5 Hz,1H),

7.90 (d, J=7.5 Hz, 1H), 7.85 (d, J=8.4 Hz, 1H), 7.70 (dd, J=1.5 Hz,J=8.1 Hz, 1H), 7.46 (ddd, J=1.2 Hz, J=7.2 Hz, J=8.4 Hz, 1H), 7.39 (ddd,J=1.2 Hz, J=7.2 Hz, J=8.4 Hz, 1H), 7.22 (s, 1H), 6.92 (s, 1H), 2.64 (t,J=7.5 Hz, 2H), 1.75-1.62 (m, 2H), 1.42-1.20 (m, 10H), 0.89 (t, J=6.6 Hz,3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 23.

Example 8

Comp. No. 12 was synthesized as follows by a coupling reaction of Comp.No. 24-5 shown below (Example 20) and thienylstannane based on thesynthesis scheme of Comp. No. 24.

An argon gas was bubbled through a toluene solution (2.5 mL) containingComp. No. 24-5 (113 mg, 0.223 mmol) and tributyl-2-thienylstannane(Tokyo Chemical Industry Co., Ltd., 103 mg, 0.27 mmol) for 10 minutes,and tetrakis(triphenylphosphine)palladium (13 mg, 0.011 mmol) was addedthereto and reacted at 95° C. for 18 hours. Further,tributyl-2-thienylstannane (42 mg) andtetrakis(triphenylphosphine)palladium (8 mg) were added and afterreaction for 8 hours, the reaction solution was diluted with chloroform,washed in sequence with water, with an aqueous saturated potassiumfluoride solution and with water. The lower layer was filtered with ananhydrous sodium sulfate layer and then concentrated to dryness, and theobtained solid was crystallized from chloroform-petroleum benzine toobtain 60 mg (yield: 58%) of the compound of Comp. No. 12.

H-nmr (500 MHz, CDCl₃): δ 8.12 (d, 1H, J>1 Hz, H-6), 7.84 (d, 1H, J=8.3Hz, H-9), 7.78 (d, 1H, J=8.3 Hz, H-4), 7.72 (br. s, 1H, H-1), 7.70 (dd,1H, J 1.8, 8.3 Hz, H-8), 7.40 (dd, 1H, J up to 1, 3.7 Hz, H-5′ (′denotethiophene)), 7.32 (dd, 1H, J up to 1, 5 Hz, H-3′), 7.29 (dd, 1H, J up to1, up to 8 Hz, H-3), 7.12 (dd, 1H, J 3.7, 5 Hz, H-4′), 2.76 (t, 2H, J upto 7 Hz, ArCH2), 1.70 (quint. 2H, J up to 7 Hz, ArCH2CH2),

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 24.

up to 1.2, up to 1.4 (m, 14H, CH2×7), 0.88 (t, 3H, J up to 7 Hz, CH3).

Example 9

Comp. No. 13 was synthesized by the following method.

In an argon atmosphere, 2-iodo[1][benzothieno[3,2-b][1]benzothiophene(190 mg, 0.52 mmol), bis(pinacolate)diborane (150 mg, 0.59 mmol),potassium acetate (76 mg, 0.77 mmol) and[1,1′-bis(diphenylphosphino)ferrocene]palladium chloride dichloromethaneadduct (PdCl₂(dppf), 7 mg (0.008 mmol) were made into adimethylsulfoxide (3 ml) solution, and the solution was heated withstirring at 90° C. for 19 hours. Water was added to the reactionsolution and after filtering out insoluble matters, the filtrate wasextracted with chloroform, washed with water and dried over magnesiumsulfate. After concentrating under reduced pressure, the residue waspurified by column chromatography to obtain 140 mg (yield: 74%) of2-([1]benzothieno[3,2-b][1]benzothiophene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane.

¹H-NMR (300 MHz, CDCl₃, δ): 8.40 (s, 1H), 7.93-7.88 (m, 4H),

7.44 (ddd, J=0.9 Hz, J=5.4 Hz, J=8.0 Hz, 1H), 7.40 (ddd, J=0.9 Hz, J=5.4Hz, J=8.0 Hz, 1H),

1.39 (s, 12H).

In an argon atmosphere,2-([1]benzothieno[3,2-b][1]benzothiophene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(150 mg, 0.59 mmol), 2-bromo-5′-octylthieno[3,2-b]thiophene (130 mg,0.39 mol) and cesium carbonate (130 g, 0.40 mmol) were dissolved in1,2-dimethoxyethane/water (10 m/1 ml), andtetrakis(triphenylphosphine)palladium (23 mg, 0.02 mmol) was addedthereto. The system was heated with stirring at 95° C. for 19 hours, andthe reaction solution was concentrated and then extracted withchloroform. The organic layer was washed with water and dried overmagnesium sulfate. After concentrating under reduced pressure, theresidue was purified by column chromatography to obtain 70 mg (yield:50%) of the compound of Comp. No. 13.

¹H-NMR (300 MHz, CDCl₃, δ): 8.13 (d, J=1.5 Hz, 1H), 7.93 (dd, J=1.5 Hz,J=7.5 Hz, 1H),

7.89 (m, 2H), 7.87 (d, J=7.5 Hz, 1H), 7.71 (dd, J=1.2 Hz, J=8.4 Hz, 1H),7.52 (s, 1H), 7.47 (ddd, J=1.5 Hz, J=7.5 Hz, J=0.6 Hz, 1H), 7.41 (ddd,J=1.5 Hz, J=7.5 Hz, J=0.6 Hz, 1H), 6.97 (s, 1H), 2.90 (t, J=7.5 Hz, 2H),1.72-1.67 (m, 2H), 1.42-1.20 (m, 10H), 0.93 (t, J=6.0 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 25.

Example 10

Comp. No. 14 was synthesized by the following method.

In an argon atmosphere, 2-iodo[1][benzothieno[3,2-b][1]benzothiophene(160 mg, 0.44 mmol), 5-octylbenzothiophene (110 mg, 0.44 mol), cesiumcarbonate (140 mg, 0.44 mmol), triphenylphosphine (12 mg, 0.04 mmol),copper iodide (84 mg, 044 mmol) and palladium acetate (5 mg, 0.02 mmol)were dissolved in dimethylformamide (5 ml), and the solution was heatedat 150° C. for 48 hours. After filtrating out insoluble matters in thereaction solution, water was added to the filtrate, and resultingsolution was extracted with chloroform, washed with water and dried overmagnesium sulfate. After concentrating under reduced pressure, theresidue was purified by column chromatography to obtain 15 mg (yield:7%) of the compound of Comp. No. 14.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=1.5 Hz, 1H), 7.96 (d, J=8.1 Hz,1H),

7.95-7.89 (m, 2H), 7.72-7.69 (m, 1H), 7.69 (s, 1H), 7.48 (d, J=6.0 Hz,1H), 7.51-7.39 (m, 4H),

2.73 (t, J=7.8 Hz, 2H), 1.77-1.60 (m, 2H), 1.42-1.20 (m, 10H), 0.88 (t,J=6.6 Hz, 3H).

Example 11

As for Comp. No. 15, 45 mg (yield: 42%) of the compound of Comp. No. 15was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (110 mg,0.30 mmol) and 2-(4-propylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(88 mg, 0.36 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=0.9 Hz, 1H), 7.94 (dd, J=0.9 Hz,J=6.3 Hz, 2H),

7.89 (d, J=5.7 Hz, 1H), 7.69 (dd, J=0.9 Hz, J=6.3 Hz, 1H), 7.61 (d,J=6.0 Hz, 2H),

7.49-7.39 (m, 2H), 7.30 (d, J=6.0 Hz, 2H), 2.66 (t, J=5.4 Hz, 2H),1.75-1.66 (m, 2H),

0.99 (t, J=5.4 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 26.

Example 12

As for Comp. No. 16, 40 mg (yield: 36%) of the compound of Comp. No. 16was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (110 mg,0.30 mmol) and 2-(4-butylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(64 mg, 0.36 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=0.9 Hz, 1H), 7.94 (dd, J=0.9 Hz,J=6.0 Hz, 2H),

7.89 (d, J=6.0 Hz, 1H), 7.69 (dd, J=0.9 Hz, J=6.3 Hz, 1H), 7.60 (d,J=6.3 Hz, 2H),

7.48-7.38 (m, 2H), 7.30 (d, J=6.3 Hz, 2H), 2.68 (t, J=6.0 Hz, 2H),1.68-1.64 (m, 2H),

1.44-1.38 (m, 2H), 0.96 (t, J=5.4 Hz, 3H).

Example 13

As for Comp. No. 17, 90 mg (yield: 78%) of the compound of Comp. No. 17was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (110 mg,0.30 mmol) and 2-(4-pentylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(100 mg, 0.36 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=0.9 Hz, 1H), 7.93 (dd, J=0.9 Hz,J=6.0 Hz, 2H),

7.89 (d, J=6.0 Hz, 1H), 7.69 (dd, J=0.9 Hz, J=6.3 Hz, 1H), 7.60 (d,J=6.3 Hz, 2H),

7.47-7.41 (m, 2H), 7.30 (d, J=6.3 Hz, 2H), 2.67 (t, J=6.0 Hz, 2H),1.70-1.60 (m, 2H),

1.37-1.32 (m, 4H), 0.92 (t, J=5.0 Hz, 3H).

Example 14

As for Comp. No. 18, 50 mg (yield: 42%) of the compound of Comp. No. 18was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (110 mg,0.30 mmol) and 2-(4-hexylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(100 mg, 0.36 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=1.2 Hz, 1H), 7.93 (dd, J=1.2 Hz,J=6.0 Hz, 2H),

7.89 (d, J=6.0 Hz, 1H), 7.69 (dd, J=1.2 Hz, J=6.3 Hz, 1H), 7.61 (d,J=6.3 Hz, 2H),

7.49-7.39 (m, 2H), 7.30 (d, J=6.3 Hz, 2H), 2.67 (t, J=6.0 Hz, 2H),1.69-1.60 (m, 2H),

1.35-1.29 (m, 6H), 0.90 (t, J=5.0 Hz, 3H).

Example 15

As for Comp. No. 19, 40 mg (yield: 32%) of the compound of Comp. No. 19was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (110 mg,0.30 mmol) and 2-(4-heptylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(110 mg, 0.36 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=0.9 Hz, 1H), 7.92 (dd, J=0.9 Hz,J=6.0 Hz, 2H),

7.89 (d, J=5.4 Hz, 1H), 7.69 (dd, J=0.9 Hz, J=6.0 Hz, 1H), 7.60 (d,J=6.3 Hz, 2H),

7.49-7.39 (m, 2H), 7.30 (d, J=6.3 Hz, 2H), 2.67 (t, J=5.7 Hz, 2H),1.70-1.68 (m, 2H),

1.35-1.25 (m, 8H), 0.89 (t, J=5.0 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 27.

Example 16

As for Comp. No. 20, 100 mg (yield: 78%) of the compound of Comp. No. 20was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (110 mg,0.30 mmol) and 2-(4-octyl phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(84 mg, 0.36 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=1.2 Hz, 1H), 7.93 (dd, J=1.2 Hz,J=6.0 Hz, 2H),

7.89 (d, J=6.0 Hz, 1H), 7.69 (dd, J=1.2 Hz, J=6.3 Hz, 1H), 7.60 (d,J=6.3 Hz, 2H),

7.47-7.39 (m, 2H), 7.30 (d, J=6.3 Hz, 2H), 2.67 (t, J=6.3 Hz, 2H),1.69-1.65 (m, 2H),

1.35-1.29 (m, 10H), 0.90 (t, J=5.1 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 28.

Example 17

As for Comp. No. 21, 120 mg (yield: 66%) of the compound of Comp. No. 21was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (160 mg,0.43 mmol) and 2-(4-nonylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(170 mg, 0.52 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=0.6 Hz, 1H), 7.92 (dd, J=0.6 Hz,J=6.3 Hz, 2H),

7.90 (d, J=5.4 Hz, 1H), 7.69 (dd, J=0.9 Hz, J=6.0 Hz, 1H), 7.60 (d,J=6.0 Hz, 2H),

7.49-7.39 (m, 2H), 7.29 (d, J=6.0 Hz, 2H), 2.67 (t, J=6.0 Hz, 2H),1.71-1.63 (m, 2H),

1.35-1.28 (m, 12H), 0.87 (t, J=5.4 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 29.

Example 18

As for Comp. No. 22, 130 mg (yield: 66%) of the compound of Comp. No. 22was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (160 mg,0.43 mmol) and 2-(4-decanylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(180 mg, 0.52 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=0.9 Hz, 1H), 7.92 (d, J=6.3 Hz,2H),

7.89 (d, J=6.0 Hz, 1H), 7.69 (dd, J=1.2 Hz, J=6.3 Hz, 1H), 7.61 (d,J=6.0 Hz, 2H),

7.47-7.41 (m, 2H), 7.29 (d, J=6.0 Hz, 2H), 2.67 (t, J=6.0 Hz, 2H),1.69-1.65 (m, 2H),

1.35-1.27 (m, 14H), 0.86 (t, J=4.8 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 30.

Example 19

As for Comp. No. 23, 120 mg (yield: 58%) of the compound of Comp. No. 23was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (160 mg,0.43 mmol) and2-(4-dodecanylphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (250 mg,0.52 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.11 (d, J=0.9 Hz, 1H), 7.93 (dd, J=0.9 Hz,J=6.0 Hz, 2H),

7.89 (d, J=6.0 Hz, 1H), 7.69 (dd, J=1.2 Hz, J=6.3 Hz, 1H), 7.60 (d,J=6.0 Hz, 2H),

7.49-7.39 (m, 2H), 7.29 (d, J=6.3 Hz, 2H), 2.66 (t, J=6.0 Hz, 2H),1.70-1.63 (m, 2H),

1.35-1.27 (m, 18H), 0.88 (t, J=4.8 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 31.

Example 20

Comp. No. 24 was synthesized from [1]benzothieno[3,2-b][1]benzothiophene(simply referred to as BTBT) by the method described below according tothe scheme shown in (Chem. 15). Incidentally, in the following scheme,Compound Nos. (4-1) to (4-5) mean (24-1) to (24-5), respectively, andCompound No. (4) means (24).

Comp. No. 24-2 (2-decylBTBT) was synthesized from BTBT in two steps(Friedel-Crafts acylation, Wolff-Kishner reduction) according toliteratures (Liquid Crystals, 2004, 31, 1367-1380 and Collect. Czech.Chem. Commun., 2002, 67, 645-664).

Synthesis of Comp. No. 24-3 (2-decyl-7-nitroBTBT)

A dichloromethane (160 mL) solution of Comp. No. 24-2 (2.48 g, 6.52mmol) was cooled to −50° C. (precipitate solids), and a 1.2Mdichloromethane solution (12 mL) of fuming nitric acid was addeddropwise over 30 minutes. After further stirring at −50° C. for 2 hours,an aqueous saturated sodium hydrogencarbonate solution (up to 13 mL) wasadded to stop the reaction. The lower layer was separated, washed with a10% saline solution, dried over anhydrous magnesium sulfate andconcentrated to dryness to obtain a crude solid (2.75 g). This solid wasrecrystallized from 2-butanone (up to 40 mL) to obtain 1.86 g (yield,67%) of a yellow crystal of Comp. No. 24-3.

H-nmr (270 MHz, CDCl₃): δ8.83 (d, 1H, J=2.2 Hz, H-6), 8.31 (dd, 1H, J8.8, 2.2 Hz, H-8), 7.92 (d, 1H, J=8.8 Hz, H-9), 7.84 (d, 1H, J=8.2 Hz,H-4), 7.75 (d, 1H, J=1.4 Hz, H-1), 7.33 (dd, 1H, J 8.2, 1.4 Hz, H-3),2.78 (t, 2H, J up to 7.5 Hz, ArCH2), 1.71 (quint. 2H, J up to 7.5 Hz,ArCH2CH2), up to 1.2, up to 1.4 (m, 14H, CH2×7), 0.88 (t, 3H, J up to 7Hz, CH3).

Synthesis of Comp. No. 24-4 (7-decylBTBT-2-amine)

Comp. No. 24-3 (1.28 g, 30 mmol) and tin (0.92 g) were suspended inacetic acid (15 mL), and concentrated hydrochloric acid (2.7 mL) wasslowly added dropwise at about 70° C. under heating and stirring. Thereaction was allowed to further proceed at 100° C. for one hour andafter cooling to 10° C. or less, a solid was collected by filtration.This solid was immersed in chloroform (up to 100 mL), washed in sequencewith concentrated aqueous ammonia and with a saturated saline solution,dried over anhydrous magnesium sulfate and then concentrated to drynessto obtain a crude solid (1.1 g). This solid was purified by separationon a silica gel column (chloroform-cyclohexane of 1:1, 1% triethylaminewas added) and crystallized from petroleum benzine to obtain 0.86 g(yield, 72%) of Comp. No. 24-4 as a faintly grey compound.

H-nmr (270 MHz, CDCl3): δ 7.68 (d, 1H, J=8.2 Hz, H-9), 7.67 (broadeneds, 1H, H-6),

7.62 (d, 1H, J 8.4 Hz, H-4), 7.23 (dd, 1H, J 1.5, 8.2 Hz, H-8), 7.16 (d,1H, J up to 2 Hz, H-1), 6.81 (dd, 1H, J up to 2, 8.4 Hz, H-3), 3.84(slightly broadened s, up to 2H, NH2), 2.73 (t, 2H, J up to 7.5 Hz,ArCH2), 1.68 (quint. 2H, J up to 7.5 Hz, ArCH2CH2), up to 1.2, up to 1.4(m, 14H, CH2×7), 0.87 (t, 3H, J up to 7 Hz, CH3).

Synthesis of Comp. No. 24-5 (2-decyl-7-iodoBTBT)

To a dichloromethane (15 mL) solution of Comp. No. 24-4 (396 mg, 1mmol), BF3-Et2O (216 mg) and tert-butyl nitride (126 mg) were addeddropwise under cooling at −15° C. The reaction temperature was raised to5° C. in about 1 hour, and a dichloromethane-THF mixed solution (1:2, 3mL) of iodine (400 mg), potassium iodide (330 mg) and tetrabutylammoniumiodide (25 mg) was added. The reaction was allowed to further proceedfor 8 hours under heating and refluxing, and the reaction solution wasdiluted with chloroform, washed in sequence with 10% sodium thiosulfate,with 5M sodium hydroxide and with a 10% saline solution, dried overanhydrous sodium sulfate and concentrated to dryness. The obtained darkbrown crude solid (500 mg) was purified by silica gel column(chloroform-hexane, 1:1), recrystallized from chloroform-methanol andfurther recrystallized from ligroin to obtain 228 mg (yield, 45%) of thecompound of Comp. No. 24-5.

H-nmr (500 MHz, CDCl₃): δ 8.23 (d, 1H, J 1.4 Hz, H-6), 7.77 (d, 1H, J8.2 Hz, H-4), 7.72 (dd, 1H, J 1.4, 8.2 Hz, H-8), 7.71 (d, 1H, J 1.4 Hz,H-1), 7.59 (d, 1H, J 8.2 Hz, H-9), 7.29 (dd, 1H, J 1.4, 8.2 Hz, H-3),2.76 (t, 2H, J 7.8 Hz, ArCH2), 1.69 (quint., 2H, J up to 7.5 Hz,ArCH2CH2), up to 1.2, up to 1.4 (m, 14H, CH2×7), 0.88 (t, 3H, J up to 7Hz, CH3).

Synthesis of Comp. No. 24 (2-decyl-7-phenylBTBT)

To a dioxane (8 mL) solution of Comp. No. 24-5 (228 mg, 0.45 mmol), 2Mtripotassium phosphate (0.45 mL) and phenylboronic acid (Tokyo ChemicalIndustry Co., Ltd., 110 mg, 0.9 mmol) were added. After bubbling anargon gas for 20 minutes, tetrakis(triphenylphosphine)palladium (TokyoChemical Industry Co., Ltd., 30 mg, 0.025 mmol) andtricyclohexylphosphine (Wako Pure Chemical Industries, Ltd., 13 mg,0.045 mmol) were added, and the system was heated with stirring at 95°C. for 22 hours. The reaction solution was diluted with chloroform andwashed with a 10% saline solution, and the lower layer was concentratedto dryness to obtain a crude solid (293 mg). This solid wasrecrystallized from toluene to obtain 130 mg (yield, 63%) of thecompound of Comp. No. 24.

H-nmr (500 MHz, CDCl₃): δ 8.12 (d, 1H, J 1.8 Hz, H-6), 7.92 (d, 1H, J8.2 Hz, H-9), 7.79 (d, 1H, J 7.8 Hz, H-4), 7.73 (br. s, 1H, H-1), 7.69(d×2, 3H, H-8, 2′,6′ (′denote Ph)), 7.49 (t, 2H, J up to 8 Hz, H-3′,5′),7.38 (tt, 1H, J>1, up to 8 Hz, H-4′), 7.29 (dd, 1H, J>1, 7.8 Hz, H-3),2.77 (t, 2H, J up to 7 Hz, ArCH2), 1.70 (quint. 2H, J up to 7 Hz,ArCH2CH2), up to 1.2, up to 1.4 (m, 14H, CH2×7), 0.88 (t, 3H, J up to 7Hz, CH3).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 32.

Example 21

As for Comp. No. 25, 13 mg (yield: 8%) of the compound of Comp. No. 25was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (130 mg,0.35 mmol) and2-(2-octyl-6-naphthyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (140 mg,0.39 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.26 (s, 1H), 8.09 (m, 1H), 8.00-7.79 (m,6H),

7.68 (dd, J=1.2 Hz, J=8.4 Hz, 1H), 7.49-7.35 (m, 4H), 2.80 (t, J=7.5 Hz,2H), 1.76-1.71 (m, 2H),

1.39-1.28 (m, 10H), 0.88 (t, J=6.9 Hz, 3H).

Example 22

As for Comp. No. 26, 25 mg (yield: 12%) of the compound of Comp. No. 26was obtained from 2-iodo[1][benzothieno[3,2-b][1]benzothiophene (150 mg,0.41 mmol) and 2-(4-octylbiphenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(190 mg, 0.49 mol) by the same method as in Example 1.

¹H-NMR (300 MHz, CDCl₃, δ): 8.19 (s, 1H), 7.95 (dd, J=1.2 Hz, J=8.1 Hz,1H),

7.99-7.90 (m, 3H), 7.80-7.69 (m, 6H), 7.60 (d, J=7.8 Hz, 2H), 7.50-7.33(m, 2H), 2.67 (t, J=7.5 Hz, 2H), 1.90-1.85 (m, 2H), 1.41-1.30 (m, 10H),0.88 (t, J=6.6 Hz, 3H).

Example 23

Comp. No. 27 was synthesized by the following method.

Naphto[2,3-b]thiophene (0.50 g, 2.7 mmol) was dissolved in THF (20 ml),and the solution was cooled to 0° C. Subsequently, n-butyllithium (a1.6M hexane solution, 1.7 ml (2.8 mmol)) was added dropwise, and thereaction solution was stirred at 0° C. for 1 hour. Further, a THF (2 ml)solution of tributyltin chloride (0.91 g, 2.8 mmol) was added dropwise.The reaction solution was returned to room temperature and stirred for 3hours. Diethyl ether (65 ml) was added to the reaction solution andafter stirring for a while, insoluble matters were filtered out. Thefiltrate was concentrated under reduced pressure to obtain a brown oilymatter. The oily matter was dissolved in toluene (30 ml), and2-bromo-5-octylthiophene (0.55 g, 2.0 mmol) andtetrakis(triphenylphosphine)palladium (97 mg, 0.08 mmol) were added. Inan argon atmosphere, the system was heated with stirring at 95° C. for17 hours, and the reaction solution was filtered to obtain a yellowprecipitate. The precipitate was washed with toluene, then dried andrecrystallized from hexane to obtain 0.39 g (yield: 52%) of the compoundof Comp. No. 27.

¹H-NMR (300 MHz, CDCl₃): 8.23 (s, 1H) 8.17 (s, 1H), 7.94-7.85 (m, 2H),

7.47-7.39 (m, 2H), 7.38 (s, 1H), 7.16 (d, J=3.6 Hz, 1H), 6.75 (d, J=3.6Hz, 1H),

2.83 (t, J=7.8 Hz, 2H), 1.76-1.62 (m, 2H), 1.45-1.24 (m, 10H), 0.91 (t,J=6.6 Hz, 3H).

this substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 33.

Example 24

Comp. No. 28 was synthesized by the following method.

To an anhydrous THF 40 ml solution of 2-bromoanthracene (0.5138 g, 0.002mol) and 4-dodecylbenzeneboronic acid (0.5976 g, 0.002 mol), cesiumfluoride (0.607 g, 0.004 mol) and tetrakis(triphenylphosphine)palladium(34.7 mg, 1.5 mol %) were added. After refluxing for 48 hours, thereaction solution was cooled to room temperature, then filtered andthoroughly washed with methanol to obtain 0.480 g of a crude crystal.Further, purification by silica gel column chromatography (eluent:cyclohexane) and recrystallization from n-hexane were performed toobtain 0.390 g (yield, 46%) of a pale yellow crystal of Comp. No. 28.

H-nmr (500 MHz, CDCl₃): δ8.46 (s, 1H), 8.43 (s, 1H), 8.16 (s, 1H), 8.07(d, 1H), 8.0 (m, 2H), 7.76 (dd, 1H), 7.70 (d, 2H), 7.46 (m, 2H), 7.32(d, 2H), 2.68 (t, 2H), 1.68 (t, 2H), 1.54 (s, 2H), 1.38-1.24 (m, 18H),0.88 (t, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 34.

Example 25

Comp. No. 29 was synthesized by the following method.

Synthesis of Comp. No. 29 (2-(5-hexyl-2-thienyl) anthracene)

To a toluene solution of 2-bromoanthracene (0.5138 g, 0.002 mol) andtributyl-(5-hexyl-2-thienyl)-stannane (0.670 g, 0.002 mol),tetrakis(triphenylphosphine)palladium (67.0 mg) was added. Afterrefluxing for 24 hours, the reaction solution was cooled to roomtemperature, poured in water (50 ml), extracted with dichloromethaneseveral times, washed with 6M HCl and water, and dried over magnesiumsulfate, and the solvent was removed by pressure reduction. After silicagel chromatography (eluent: cyclohexane), recrystallization fromn-hexane was performed to obtain 0.310 g (yield, 50%) of a pale yellowcrystal of Comp. No. 29.

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 35.

Example 26

Comp. No. 30 was synthesized by synthesizing anthra[2,3-b]thiophene-5,10dione, reducing this compound to obtain anthra[2,3-b]thiophene,converting it to 2-tributylstannyl-anthra[2, 3-b]thiophene, andperforming coupling with 4-dodecyl-bromobenzene.

Thiophene-2,3-dicarboaldehyde (2.8 g, 0.020 mol),1,4-dihydroxynaphthalene (3.2 g, 0.020 mol) and dry pyridine (20 ml)were refluxed in argon for 6 hours and after cooling to roomtemperature, about 50 ml of water was added. The precipitated solid wasfiltered and thoroughly washed with water, ethanol and acetone to obtain3.28 g (yield, 62%) of a dark brown solid.

Hnmr: (500 MHz, CDCl₃): δ8.82 (s, 1H), 8.73 (s, 1H), 8.34-8.31 (m, 2H),7.79-7.77 (dd, 2H), 7.76-7.74 (d, 1H), 7.56-7.55 (d, 1H).

Anthra[2,3-b]thiophene-5,10 dione (2.64 g, 0.010 mol) was added to dryTHF (100 ml) cooled to 0° C., in which lithium aluminum hydride (LiAlH₄,1.52 g, 0.040 mol) was added, and the system was stirred at 0° C. forabout one hour. Further, 0.76 g of LiAlH₄ was added, and the system wasstirred at room temperature for 2 hours. While cooling at 0° C., 100 mlof 6 M-hydrochloric acid was added little by little. The reactionsolution was returned to room temperature and held for about 30 minutes,and the precipitated solid was filtered and washed with water, ethanol,ethyl acetate and hexane (crude yield: 1.67 g, 71%). Thereafter, silicagel chromatography (eluent: toluene) was performed to obtain 1.20 g(yield: 49%) of a yellow crystal.

Hnmr: (500 MHz, CDCl₃): δ8.59 (s, 1H), 8.53 (s, 1H), 8.51 (s1H), 8.49(s, 1H), 8.0-7.99 (dd, 2H), 7.48-7.46 (d, 1H), 7.43-7.40 (dd, 2H),7.40-7.39 (d, 1H).

Anthra[2,3-b]thiophene (0.702 g, 0.003 mol) dissolved in dry THF (10ml), and the solution was cooled to −78° C. Subsequently, 1.88 ml ofn-BuLi (1.6 M/hexane solution) was added, and the system was stirredabout one hours. Further, tributylstannyl chloride (9.977 g, 0.003 mole)was added, and the temperature was raised to room temperature. Thesystem was stirred for 2 hours and after adding dichloromethane, theresulting solution was washed with an aqueous saturated ammoniumchloride solution, then with water and further with a saturated salinesolution, and dried over sodium sulfate. The solvent was removed underreduced pressure, and the residue was subjected to the next reaction.

Tetrakis(triphenylphosphine)palladium (2 mol %) was added to a dry THFsolution of 2-tributylstannyl-anthra[2,3-b]thiophene (0.003 mol) and4-dodecyl-bromobenzene (1.07 g, 0.003 mol) and refluxed for 24 hours.The reaction solution was cooled to room temperature, poured in 50 ml ofwater and extracted with dichloromethane. The organic phase was washedwith 6M hydrochloric acid and water and dried over magnesium sulfate,and the solvent was removed by pressure reduction. The residue waspurified by silica gel chromatography (eluent:cyclohexane→cyclohexane/toluene=2/1).

As a result, 0.15 g (yield, 10.5%) of a yellow crystal was obtained.

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 36.

Example 27 to Example 30

In these Examples, the compounds of Comp. No. 49 to Comp. No. 52 shownbelow were synthesized under the same conditions as in Examples above bya Suzuki coupling reaction of 2-decyl-7-iodoBTBT and a correspondingboronic acid (p-methylphenylboronic acid, m-methylphenylboronic acid,o-methylphenylboronic acid and 5-methyl-2-thiopheneboronic acid,respectively; all produced by Wako Pure Chemical Industries, Ltd.).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIGS. 38 to 41.

Example 31 Synthesis of Comp. No. 53: 2-decyl-7-perfluorophenyl BTBT(FP-BTBT-10)

(Introduction of a perfluorophenyl group is known to be difficult undernormal conditions of the Suzuki reaction and therefore, the compound wassynthesized by the method described in the literature (Organic Letters7, 4915, 2005)).

Pentafluorophenylboronic acid (Aldrich, 80 mg), Pd2(dba)3(tris(dibenzylideneacetone)dipalladium, 14 mg), tri-tert-butylphosphine(0.012 mL), Ag2O (83 mg) and CsF (91 mg) were added to a DMF (4 mL) andDME (2 mL) solution of 2-decyl-7-iodoBTBT (152 mg, 0.3 mmol) and afterbubbling of an argon gas for 10 minutes, reacted at 100° C. for 20hours. The solid was removed by filtration, washed with chloroform andconcentrated, and the residue was solidified from methanol-water andcollected by filtration (100 mg). This solid was adsorbed on silica gelfrom a chloroform solution, placed on silica gel column, eluted withcyclohexane and thereby purified. The eluting solution was concentratedto dryness (46 mg) and recrystallized from chloroform-isooctane toobtain 32 mg (yield, 20%) of Comp. No. 53.

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 42.

Example 32 Comp. No. 54: 2-cyclohexene-1-yl-7-decylBTBT (Che-BTBT-10)Comp. No. 55: 2-cyclopenten-1-yl-7-decylBTBT (CPe-BTBT-10)

As shown below, Comp. No. 54 and Comp. No. 55 were synthesized under thesame conditions by a Suzuki reaction of 2-decyl-7-iodoBTBT withcyclohexeneboronic acid pinacol ester (A, Aldrich) andcyclopenteneboronic acid pinacol ester (B, synthesized according to J.Org. Chem. 74, 7715, 2009), respectively.

Synthesis Example of Comp. No. 55

To a dioxane (6 mL) solution of 2-decyl-7-iodoBTBT (135 mg, 0.267 mmol)and reagent B (103 mg, 0.53 mmol), 2M tripotassium phosphate (0.27 mL)was added and after bubbling of an argon gas for 20 minutes,tetrakis(triphenylphosphine)palladium (15 mg) and tricyclohexylphosphine(7 mg) were added and reacted at 100° C. for 24 hours. The reactionsolution was cooled, and the produced solid was collected by filtration.This solid (100 mg) was adsorbed on silica gel from a chloroformsolution, placed on silica gel column, eluted withcyclohexane-chloroform (20:1) and concentrated, and the produced solidwas collected by filtration. This solid (56 mg) was recrystallized fromligroin to obtain 54 mg (yield: 45%) of Comp. No. 55.

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIGS. 43 to 44.

Example 33 Comp. No. 56: 1-(7-decylBTBT-2-)piperidine (Pip-BTBT-10)

(Synthesis According to Conditions of Buchwald-Hartwig Reaction)

To a toluene solution (2 mL) of 2-decyl-7-iodoBTBT (51 mg, 0.1 mmol) andpiperidine (10 mg), NaOtBu (13 mg), Pd2(dba)3 (up to 4 mg) and racBINAP(up to 4 mg) were added and reacted at 95° C. for 40 hours. After anordinary post-treatment with chloroform, the crude solid (46 mg) waspurified by silica gel column (cyclohexane-chloroform, 2:1) andsubsequently by alumina column (cyclohexane-chloroform, 4:1) andrecrystallized from IPA-ligroin to obtain 9.2 mg (yield, 20%) of Comp.No. 56.

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 45.

Example 34 Comp. No. 57: 1-(7-decylBTBT-2-)1H pyrrole (Pyr-BTBT-10)

To a toluene solution (1 mL) of 7-decyl-BTBT-2-amine (40 mg, 0.1 mmol),acetic acid (0.5 mL) and 2,5-dimethoxytetrahydrofuran (40 mg, 0.3 mmol)were added, and the system was heated at 95° C. for 4 hours. After anordinary post-treatment with chloroform, the obtained crude solid (42mg) was purified by silica gel column (cyclohexane) and recrystallizedfrom ligroin to obtain 15 mg (yield, 34%) of Comp. No. 57.

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 46.

Example 35 Comp. No. 58: 7,7′-(tetramethylbiphenyl)-bis(2-decylBTBT)(Me4BP (10-BTBT)2)

The compound was synthesized according to the following scheme.Diboronic acid pinacol ester (C, novel compound) was synthesized from D(J. Amer. Chem. Soc. 131, 13074, 2009) according to the Miyaura-Ishiyamamethod.

i: Synthesis of C

To a DMSO (8 mL) solution of Compound D (231 mg, 0.5 mmol) and CompoundE (bis(pinacolato)diboron, 290 mg, 0.63 mmol), PdCl2(dppf)-CH₂Cl₂ (43mg) and potassium acetate (300 mg) were added and after bubbling of anargon gas for 10 minutes, reacted at 90° C. for 21 hours. The reactionsolution was extracted with diisopropyl ether, washed with a (10 mL×3)10% saline solution, dried over magnesium sulfate, concentrated todryness and then purified by silica gel column (cyclohexane-ethylacetate, 19:1) to obtain 206 mg (yield, 89%) of Compound C.

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 47.

ii: Synthesis of Comp. No. 58

To a dioxane (7 mL) solution of Compound C (69 mg, 0.15 mmol) and2-decyl-7-iodoBTBT (190 mg, 0.375 mmol), 2M tripotassium phosphate (0.3mL) was added and after bubbling of an argon gas for 10 minutes,tetrakis(triphenylphosphine)palladium (14 mg) and tricyclohexylphosphine(7 mg) were added and reacted at 95° C. for 45 hours. After an ordinarypost-treatment with chloroform, the obtained crude solid (200 mg) wasadsorbed on silica gel from the chloroform solution, placed on silicagel column (cyclohexane-cyclohexane-chloroform, 5:1), thereby purified,and subsequently recrystallized from chloroform-ligroin to obtain 36 mg(yield, 25%) of Comp. No. 58.

Example 36

In an argon atmosphere,2-bromobenzo[d,d′]thieno[3,2-b;4,5-b′]dithiophene (120 mg, 0.36 mmol),2-(5-octylthiophene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (130 mg,0.41 mmol) and cesium carbonate (180 mg, 0.54 mmol) were dissolved inDMF (5 ml), and tetrakis(triphenylphosphine)palladium(0) (8 mg, 007mmol) was added thereto. The system was heated with stirring at 95° C.for 20 hours, and the reaction solution was extracted with ethylacetate, washed with water and then dried over magnesium sulfate. Theethyl acetate layer was concentrated, and the residue was purified bycolumn chromatography to obtain 20 mg (yield: 13%) of Comp. No. 59.

¹H-NMR (500 MHz, CDCl₃, δ): 7.86 (d, J=7.5 Hz, 1H), 7.80 (d, J=8.5 Hz,1H), 7.43 (t, J=8.0 Hz, 1H), 7.35 (t, J=8.0 Hz, 1H), 7.34 (s, 1H), 7.05(d, J=4.0 Hz, 1H), 6.72 (d, J=4.0 Hz, 1H), 2.85 (d, J=8.0 Hz, 2H), 1.72(m, 2H), 1.28 (m, 10H), 0.89 (t, J=7.0 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 48.

Example 37

From 2-bromobenzo[d,d′]thieno[3,2-b;4,5-b′]dithiophene (73 mg, 0.22mmol) and 4-octylphenylboranic acid (61 mg, 0.26 mol), 57 mg (yield:60%) of Comp. No. 60 was obtained by the same method as in Example 36.

¹H-NMR (500 MHz, CDCl₃, δ): 7.87 (d, J=7.5 Hz, 1H), 7.82 (d, J=7.5 Hz,1H), 7.57 (d, J=8.5 Hz, 2H), 7.53 (s, 1H), 7.44 (t, J=7.5 Hz, 1H), 7.35(t, J=7.3 Hz, 1H), 7.24 (d, J=8.5 Hz, 2H), 2.63 (t, J=7.5 Hz, 2H), 1.64(m, 2H), 1.30 (m, 10H), 0.89 (t, J=7.5 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 49.

Example 38

In an argon atmosphere,2-(naphtho[2,3-b]thienyl-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane(130 mg, 0.41 mmol) and cesium carbonate (200 mg, 063 mmol) weredissolved in DMF (5 ml), and tetrakis(triphenylphosphine)palladium(0) (6mg, 005 mmol) was added thereto. The system was heated with stirring at95° C. for 19 hours, and the reaction solution was extracted withdichloromethane, washed with water and then dried over magnesiumsulfate. The dichloromethane layer was concentrated, and the residue waspurified by column chromatography to obtain 50 mg (yield: 32%) of thecompound of Comp. No. 61.

¹H-NMR (500 MHz, CDCl₃, δ): 8.30 (s, 1H), 8.24 (s, 1H), 7.95 (t, J=4.5Hz, 1H), 7.89 (t, J=4.5 Hz, 1H), 7.68 (d, J=8.5 Hz, 2H), 7.61 (s, 1H),7.45 (m, 1H), 7.28 (d, J=8.5 Hz, 2H), 2.65 (d, J=7.0 Hz, 2H), 1.64 (m,2H), 1.26 (m, 10H), 0.89 (t, J=7.0 Hz, 3H).

This substance was subjected to the screening method described in thisspecification, so as to observe the texture thereof. The thus obtainedobservation results are shown in FIG. 50.

Example 39

FIGS. 17 to 54 show results of texture observation under a polarizingmicroscope aiming at screening for the preferred liquid crystalsubstance specified in the description of the present invention. In thetexture observed at 20° C., a black linear or fine region due to a crackor a void was observed, but in the phase appearing in the temperatureregion before crystallization, a black line or region was not observed,and it could be confirmed that the texture is apparently not a nematicphase characteristic of a Schlieren texture or SmA or SmC phasecharacteristic of Fan-like texture but is a higher-order phase. In thelight of this screening, these substances could be identified as thepertinent substance of the present invention.

Example 40

Out of Comp. No. 5 to Comp. No. 61 measured by the scanning differentialthermal analyzer, the phase transition behaviors of the compounds shownin the Tables are shown in Tables 9 to 15.

I stands for an isotropic phase, N stands for a nematic phase, SmAstands for a smectic A phase, SmE stands for a smectic E phase, SmXstands for a highly-ordered smectic phase or a metastable crystal phase,and K stands for a crystal phase.

Example 41

In order to verify that a liquid crystal substance designed andsynthesized according to this method exhibits very excellent propertiesas an organic semiconductor, examples where the mobility was expected byperforming the measurement of transient photocurrent by a time-of-flightmethod are shown in Tables 17 and 18.

The measurement was performed by the following method. A cell having acell thickness of 13 to 17 μm (commercial product; manufactured by EHC),in which two ITO transparent electrode-attached glass substrates arelaminated together by a thermosetting resin including a spacer, washeated to the isotropic phase temperature of each compound, and a smallamount of a sample was put into contact with the opening part of thecell so as to inject the sample into the cell by utilizing a capillaryphenomenon. The cell was fixed on a sample stage having a heaterpositioned therein, and a DC voltage was applied to the electrode. Anitrogen laser pulsed light having a pulse width of 600 ps was radiated,and the current flowing upon irradiation was measured by a digitaloscilloscope. At this time, attention was paid not to cause a waveformdistortion due to a space charge by adjusting the light irradiationintensity such that the integral value (charge amount) of thephotocurrent flowing upon light irradiation falls within 10% of thegeometric capacitance of the cell.

In the transient photocurrent waveform measured at 150° C. correspondingto SmE phase of Comp. No. 9, as shown in FIGS. 5 and 6, a shouldershowing a distinct charge transit appeared. When the charge transit timewas estimated from the shoulder and the mobility was calculated, in thecase of applying a positive volume to the light irradiation-sideelectrode, that is, under the condition of the hole transport governingthe current, the mobility was 0.2 cm²/Vs, and in the case of applying anegative volume, that is, under the condition of the electron transitgoverning the current, the mobility was similarly very high and was 0.2cm²/V. These mobilities were confirmed to be independent of the electricfield. As apparent from these results, this substance has highphotoconductivity and high mobility and therefore, exhibits excellentproperties as an organic semiconductor. Further, in the measurement oftransient photocurrent by this time-of-flight method, a photocurrentcorresponding to the irradiation with pulsed light was observed, and asapparent from this, a high-speed optical signal associated with lightirradiation was obtained, demonstrating that the substance can beutilized for a photosensor having a high response speed.

Example 42

Similarly to Example 41, Comp. No. 10 was measured for the transientphotocurrent at 200° C. exhibiting its SmE phase by using a cell with athickness of 13 μm and using the time-of-flight method, as a result, awaveform shown in FIG. 7 was obtained. As apparent from this waveform, ashoulder corresponding to a hole transit time was observed and when thehole mobility was estimated from the transit time, a high value of 0.2cm²/Vs was obtained. The calculated mobility at the applied voltage wasconfirmed to be independent of the electric field.

Example 43

Similarly to Example 41, after injecting Comp. No. 20 into a cell with athickness of 16 μm, Comp. No. 20 was measured for the transientphotocurrent at 170° C. corresponding to SmE phase by the time-of-flightmethod, as a result, a shoulder exhibiting the transit time was observedin the waveform as shown in FIG. 8 and the transit time could bedetermined. When the mobility was estimated from the value, a value of0.1 cm²/Vs was obtained as the hole mobility.

Example 44

Similarly to Example 41, Comp. No. 28 was, as shown in FIG. 9, measuredfor the transient photocurrent at 150° C. of a highly-ordered smecticphase (Smx phase) and when the mobility was estimated, a very high valueof 0.3 cm²/Vs was obtained as the hole mobility. This hole mobility maybe a highest value among Heretofore known rod-like liquid crystalsubstances.

Example 45

The measurement of a transient photocurrent by the time-of-flight methodmay be an effective method capable of directly calculating the mobilityand confirming the usefulness as an organic semiconductor material, butin order to more empirically demonstrate the usefulness as an organicsemiconductor material, FET was manufactured using the synthesizedliquid crystal substance and properties thereof were examined.

Specific Manufacturing Method of Organic Transistor:

The manufactured organic transistor had a structure shown in FIG. 10.Specifically, an organic semiconductor layer was formed on a substrateand thereafter, source and drain electrodes were vacuum depositedthrough a metal mask to manufacture the transistor. Details thereof aredescribed below.

<Substrate>

A heavy doped silicon wafer (P⁺−Si) and a thermally oxidized silicon(SiO₂, thickness: 300 nm) were used as the gate electrode and the gateinsulating film, respectively. The silicon wafer of the thermallyoxidized film was cut into an appropriate size (20×25 mm), and the cutsilicon wafer (hereinafter, simply referred to as substrate) wasultrasonically cleaned in sequence with neutral detergent, ultrapurewater, isopropyl alcohol (IPA), acetone and IPA.

Next, a liquid crystalline organic semiconductor compound was dissolvedin an organic solvent (diethylbenzene here) to prepare a solution. Theconcentration of the solution was set to be from 0.5 to 1 wt %. Thissolution and a glass-made pipette for coating the solution on thesubstrate were previously heated to a predetermined temperature on a hotstage, and the substrate above was placed on a spin coater provided inan oven. After raising the temperature in the oven to a predeterminedtemperature, the solution was applied on the substrate, and thesubstrate was rotated (about 3,000 rpm, 30 seconds). After stopping therotation, the substrate was swiftly taken out and cooled to roomtemperature. A liquid crystalline organic semiconductor film having athickness of 30 to 50 nm was obtained.

Subsequently, a gold electrode (from 30 to 100 nm) was vapor-depositedby a vacuum deposition method (2×10⁻⁶ Torr) on the substrate havingcoated thereon an organic semiconductor layer, whereby source and drainelectrodes were formed. The source and drain electrodes were formed atchannel length:channel width=100 μm:1,000 μm, 50 μm:1,000 μm, or 20μm:200 μm by vapor-depositing a pattern and utilizing a mask pattern.

Thereafter, the region other than the regions where source and drainelectrodes and a channel are formed was wiped off using a spongeimpregnated with toluene to simply insulate the device.

The evaluation of the manufactured organic transistor was performed in anormal air atmosphere by using a two-power source measurement unit forthe gate electrode and the drain electrode, and transmissioncharacteristics of the filed-effect transistor were examined bymeasuring the current flowing in the device. The mobility was calculatedusing the formulae of transmission characteristics and saturationcharacteristics of the saturated region (V_(DS)=−50 V).

In Table 16, the mobilities estimated from typical transmissioncharacteristics (shown in FIGS. 11 to 16) of transistors manufacturedusing the compounds recited in the Table.

FIG. 53 shows the results when each of a transistor, which has beenmanufactured by using Comp. No. 24 (P-BTBT-10) exhibiting a highlyordered SmE phase in the temperature region adjacent to the crystalphase and a transistor, which has been manufactured by usingdidecylbenzothienobenzothiophene (10-BTBT-10) exhibiting SmA phase as alow-order liquid crystal phase in the temperature region adjacent to thecrystal phase was subject to a heat stress at a predeterminedtemperature for 5 minutes and mobilities estimated from the transistorcharacteristics at room temperature were plotted based on thetemperature when applying a heat stress. The transistor, which has beenmanufactured by using Compound 24 exhibiting a highly ordered SmE phasein the temperature region adjacent to the crystal phase maintained highmobility even when heated at a temperature exceeding 150° C. for 5minutes, whereas with the compound exhibiting SmA phase that is alow-order crystal phase, the mobility was greatly reduced when heated ata temperature exceeding 100° C. for 5 minutes. It may be seen from theseresults that development of a highly ordered liquid crystal phase isvery effective in improving the heat resistance of a device.

Further, in Tables 17 and 18, SmE phase: hole mobility when using thecompounds recited in the Tables are shown.

The results obtained in Examples above are shown together in the Tablebelow.

TABLE 16 Compound (a) (b) COM5

1.8 cm²/Vs COM6

2.2 cm²/Vs COM7

3.2 cm²/Vs COM8

2.1 cm²/Vs COM9

3.6 cm²/Vs COM11

1.3 cm²/Vs COM12

1.3 cm²/Vs COM20

0.35 cm²/Vs  COM23

0.42 cm²/Vs  COM24

5.7 cm²/Vs COM27

3.6 × 10⁻²cm²/Vs COM28

0.11 cm²/Vs  COM29

0.08 cm²/Vs  COM31

1.3 cm²/Vs COM49

0.18 cm²/Vs  COM51

1.1 × 10⁻²cm²/Vs COM52

7.8 × 10⁻²cm²/Vs COM54

1.3 × 10⁻⁴cm²/Vs COM56

2.0 × 10⁻⁵cm²/Vs COM59

4.6 × 10⁻⁴cm²/Vs COM61

7.7 × 10⁻³cm²/Vs

TABLE 17 (a) Chemical structural formula, (b) phase and hole or electronmobility (cm²/Vs) Compound (a) (b) COM31

SmE phase: hole mobility 0.2 cm²/Vs COM31

SmE phase: electron mobility 0.2 cm²/Vs COM10

SmE phase: hole mobility 0.2 cm²/Vs

TABLE 18 Compound (a) (b) COM20

SmE phase: hole mobility 0.1 cm²/Vs COM28

SmX: hole mobility 0.3 cm²/Vs

INDUSTRIAL APPLICABILITY

In the liquid crystal substance produced by the present invention, thedeveloped highly ordered liquid crystal phase may have a large aromaticπ-electron fused ring system advantageous to charge transport in thecore part and accordingly, may promise high mobility, and the substancecan be utilized as a high-quality organic semiconductor being uniformand having less defects.

As for specific applications, the substance can be used for aphotosensor, an organic EL device, an organic FET, an organic solarcell, an organic memory device and the like. The transient photocurrentmeasured by the time-of-flight method in Examples is a result ofmeasuring the photocurrent of the substance to be measured, and this isa case actually utilizing the substance for a photosensor. Further, asdemonstrated in Examples, the substance can be further utilized as anorganic transistor material.

The invention claimed is:
 1. An organic semiconductor material selectedfrom the group consisting of:


2. An organic semiconductor material, comprising at least a chargetransporting molecular unit A:

 and a cyclic structure unit B selected from group consisting of

wherein in the above Formulae the mark * represents a binding positionwith respect to a unit B or a unit C, and the mark ** represents abinding position with respect to a unit A or a unit C, the organicsemiconductor material having a unit C as a side chain in at least oneof the unit A and the unit B, wherein the unit C is a hydrocarbon grouphaving a carbon number of 2 to 20, wherein the organic semiconductormaterial exhibits a liquid crystal phase selected from SmB, SmB_(cryst),SmI, SmF, SmG, SmE, SmJ, SmK and SmH, and wherein the organicsemiconductor material has a mobility of 0.1 cm²/Vs or more, in terms ofelectron mobility, hole mobility and mobility obtained from field-effecttransistor property.
 3. The organic semiconductor material according toclaim 2, wherein, when the unit A or unit B is rotated using, as theaxis, a single bond between the unit C and the unit A or unit B, theangle θ formed by a straight line linking a carbon atom bonded with theunit C and a carbon or hetero atom located on the outermost side of thecore part of the unit A or unit B and kept from directly bonding to theunit C on rotating the unit A or unit B, and said axis is 80° or less.4. The organic semiconductor material according to claim 2, wherein aliquid crystal phase selected from the group consisting of SmB,SmB_(cryst), SmI, SmF, SmG, SmE, SmJ, SmK and SmH appears adjacent to acrystal phase, when the temperature of the material is increased fromthe crystal phase thereof.
 5. The organic semiconductor materialaccording to claim 2, wherein in a cooling process of the organicsemiconductor material, any one phase of N phase, SmA phase, and SmCphase appears in advance of appearing of the liquid crystal phaseselected from the group consisting of SmB, SmB_(cryst), SmI, SmF, SmG,SmE, SmJ, SmK and SmH.
 6. The organic semiconductor material accordingto claim 2, wherein the number of repetitions of the unit A is 1 or 2.7. The organic semiconductor material according to claim 2, wherein thenumber of repetitions of the unit B is 1 or
 2. 8. The organicsemiconductor material according to claim 2, wherein the number ofrepetitions of the unit C is 1 or
 2. 9. The organic semiconductormaterial according to claim 2 wherein the temperature region in which aliquid crystal phase appears, is different in the temperature decreasingprocess and the temperature rising process.
 10. The organicsemiconductor material according to claim 2, wherein the work functionbetween the organic semiconductor material, and an electrode substanceto be used in electrical contact with the organic semiconductor materialis 1 eV or less.
 11. The organic semiconductor material according toclaim 2, wherein the electrode substance is selected from: silver,aluminum, gold, calcium, chromium, copper, magnesium, molybdenum,platinum, indium tin oxide, and zinc oxide.
 12. An organic semiconductordevice using the organic semiconductor material according to claim 2.13. An organic transistor using, as an organic semiconductor layer, theorganic semiconductor material according to claim 2.